Question

Trust me on this: you don't want to lose sleep on the many reasons why people will blacklist you.
And the answer to your question is no, they can't. If you make a giveaway, the person who blacklisted you cannot see a public/group GA so they can't enter. They can see an invite only GA if you share the link but they still won't be able to enter.

So basically, go ahead and make great GAs, that'll teach them ;)

It's gonna be okay, a lot of this website has a very community feel to it and there's certain etiquette type things you'll just pick up in time.
Some basic ones just being:

• Someone doesn't like your opinion in a comment section
• Someone doesn't like a discussion thread you made
• Someone doesn't like your giveaway ratio of sent:won gifts
• Maybe you don't play a game you won and people think you're a hoarder and don't want you winning their giveaways
• Sometimes you'll get blacklisted after winning a game from someone as away for them to ensure you can't immediately win another game from them again

I've been on this site for a few years and while these are pretty common reasons for blacklisting, I learned very recently that binge posting a bunch of garbage giveaways looks spammy and you'll probably get a handful of blacklists for taking up whole pages of the public giveaway area.
But hey, you learn from it and maybe next time I wanna give away 50+ games at one time, I'll do it in a group that appreciates that if I don't want another 10+ blacklists 😅
Blue hearts do help you feel good, even if a majority of those people don't make whitelist giveaways, it's like a "hey congrats! I like this etiquette thing you're doing, keep it up!". That said, have a blue heart from me as a welcome to the community ^-^

Only recently, I gave someone a gift.
[TL;DR]
The winner will not receive the gift I attached to the email.
I made an effort to get in touch for a week.(no reaction)
It's been a week and I tried to make a friend request on Steam and get in touch, but it was rejected.
In addition, I have been blacklisted.

It's time to use the Support Ticket.
I quickly requested the store for a gift attached to an email and invalidated it.
I consulted Support for a reroll application.

After that, winner couldn't get in touch because of the mysterious reason that the winner didn't have the habit of looking at the comment section of the winning GA.

Perhaps Winner was too busy to see it.
There must have been a mistake.
With the power of Support, we were able to give the prize to the winner and the blacklist was lifted.
Even if you are not 100% defective, it will happen due to an accident or a misunderstanding.

So don't worry about it strongly.

Answer: Don't worry about the reason.
WARNING: Stomachache, headache, insomnia, loss of coping effort, deprived of time to enjoy reality, reduced game time.

Welcome to Steamgifts. The first blacklist is meant to inform you that the tutorial is over, you beat the Phalanx, beyond the gate you will learn the community guides on how to survive out here.
it's a guarantee that you will get more just by being an active member, either by participating in GAs, entering and creating them. Or not showing gratitude for a game, or sometimes for showing too much.
don't worry about blacklists, as you are far more likely to surpass that number with whitelists.

I was also taken aback by the first occasion. People blacklist others for the silliest reasons (if there is any to begin with).
One case stands out for me. I've won a GA. I've got the key, but it was region locked (not set and not written under the GA) and could not redeem it. I kindly notified the GA creator about it. I really was not mean or in any way antagonistic, just told him that we should resolve this as I did not want him to be punished for it, nor myself for not claiming the sent key until deadline. To which he blacklisted me. XD No answer, no attempt at communication, no whatever, he straight up slammed the door in my face. Funnily, he later lifted the BL and contacted me, and we were able to agree upon a reroll, but I just cant understand why he reacted so... refusingly first.
People of all kinds are present here, expect some unusual reactions, but dont take them to heart!

I got 3 new blacklists for making a couple of giveaways this last holiday event lmao people'll literally BL you for anything here don't worry about it.