RESOLVED: I cannot create giveaways anymore :(

I don't think Ive seen this ever.

Would'nt this be related to an ad blocker of some sorts in your browsers?

No problems here. Are you running any extensions? Try disabling everything and see if the problem persists.

My first guess would be a browser extension is giving you these problems. Suspects in this case are adblockers or a Steamgifts addon (or any other addon that changes some stuff inside websites).

Are you using VPN or custom DNS? Easy way is to install Firefox and try using it to check if is browser related.

Chrome and Edge

that's the same browser basically, try FF and without any addons

endless processing loop

javascript failure, some blocking addon likely

I heard that 24H2 for Windows 11 created a whole lot of problems so maybe this is one of them. My friend reported to me that half of the older games he wants to play seem to not run under 24H2 and he had to go back to Windows 11 state before that upgrade.

I've got some weird behaviour in sites I used a lot. Here in SteamGifts sometimes appears the "Accept cookies" terms and it keeps appearing until I clean cookies/temp files for this site. So it might worth a try.

Sound's like extension?
Do u accept cookies, for SG-site?

If i had any money id bet this is an extension you use on every browser
And this bug doesnt mean its a malicious one (but could be)

Good news is that throuh the extension manager in settings (exists in every chromium browser, like edge and chrome) you can change how/when extensions works... sadly theres no blacklist of sites a extension wouldnt work, but you can set extensions to work on just some specific sites or only upon clicking on their icon.

Try SG with zero extensions. If it works start disabling one by one- disable one, reload SG, try, disable another one...

Theres also a rare chance its a bug by the interaction of 2 extensions, wich is way more headache to figure out wich ones. But testing browser with no extensions will give a hint if thats the problem at all.

Open the page to create giveaways, open the browser developer tools, go to the "network" tab, and start typing a game name in the text box, you should be seeing XHR network request being sent to /ajax.php, the response it returns is an HTML fragment to show the autocomplete results.

Can you confirm these requests are being made and nothing is blocking them on your end?

View attached image.

Maybe a 'refresh browser' or troubleshoot mode could identity if its something u added to the browser or not.
In my experience, disabling add-ons can prove ineffective.

Can you try Opera GX maybe?

Sorry if it's a stupid suggestion, but have you tried to create it from your phone (or other PC if possible)? At least to make sure it's not just your PC thing, which it might be

Wow, what a strange bug. No idea what is going on, but have some, huh, positive thoughts.

Cheers!

Ok, normally I would have suggested what the majority of other people are suggesting...that it's a browser extension or the like. But since you've clearly checked this in multiple ways, I started considering other, more esoteric things.

Since the place you're getting weird behavior is via SG web site code accessing steam through the Steam API...hmmm, maybe it's oddly something on the Steam side? Perhaps try uninstalling and reinstalling the Steam client itself? And then double-check that you don't have any blocks in place (like perhaps the built-in pop-up blocker in browsers -- and often this list is shared in windows across browsers) for any URL that is part of the overall Steam domain?

Since the rest of the site is working ok, and only features related to accessing Steam data/functions directly via the API aren't working, I'd keep digging there.

Seems like a long shot, but after eliminating all of the usual browser-side issues, it's all I've got idea-wise that can be local to your PC.

Are you experiencing any other strange behaviour on other websites?

Maybe it could be some kind of graphical glitch, have you updated the graphics card drivers recently?

starting at the same time as this problem I noticed that whenever I win a game and try to view the key I get an endless processing loop

I doubt the CPU is at fault, since you have no other issues. But just in case, you can use this to check:
https://www.intel.com/content/www/us/en/download/15951/intel-processor-diagnostic-tool.html
I tried it myself and it seems that on very old CPUs the brand name isn't detected. In this case you can use the "Tools" menu to turn off "Stop Testing On Fail".

Edit: I agree with Gilgamash that it could be caused by an anti-virus interfering. Though it would have to be an exotic one or a very strict configuration.

Have you by chance recently cancelled 2,743 giveaways?
Just kidding -- that's an impressive give record!

This is some software that is interfering. Maybe you think you have everything disabled but clearly it is not. Has to be some kind of ad blocker or antivirus or something similar. Completely remove it from your system and use a tool to make sure nothing was left behind. Same thing with your browser. If that doesn't work then I would hazard to guess there is some kind of corruption and you need to just start with a fresh install of whatever OS you use. I mean if you want to save time and be 100% sure just skip right to a fresh install.

Could you upload some screenshots of when you try? Unsure if that will help, but can't hurt. On the rare outside change, could it be you're trying to GA a game that's no longer in the database or does it happen for any and all games?

Here is what I would do for troubleshooting, to try to narrow it down.

You already tried different browsers and disabling extensions, good!

Make sure the date, time, and time zone on your computer is correct.

Some Antivirus software intercepts web activity and can cause problems. Try temporarily disable or uninstall it.

Reboot to safe mode and see if it still happens.

Try on a different computer/phone/tablet.

If your computer is a laptop, can you try to use a different internet connection? Leave home or hook up to mobile phone hotspot.

Create a new user on your computer and log into that user's profile and see if it still happens.

Use a virtual machine or Windows Sandbox and try in there.

If you have WSL set up, install Firefox in there and give it a try.

If you have an idea when this started, and have a backup or System Restore checkpoint from prior to that, try to restore back to it.

Run dism /online /cleanup-image /restorehealth in an administrator cmd prompt and see if it fixes anything. Reboot if it did.

Run sfc /scannow in an administrator cmd prompt and see if it fixes anything. Reboot if it did.

Download the latest Windows 11 ISO file, mount it and run setup.exe to do an in-place reinstall of Windows. You won't lose any files or settings (unless you specifically tell it to).

It's almost unlikely, but since you're talking about a specific game, are you sure it's in the database? Have you tried searching for a different game?

Would you share what VPN and security setting it was? It sounds so strict especially since shutting it off didn't solve the issue