I've lost a level?

The graph only shows you the progress of your CV based on the current evaluations per giveaway.

You could check your giveaways one by one and see when those got reduced or 0 CV.
I have no idea if there is an easier way to do it.

I had 0 no value games, now i have 6 of them. So u always can expect ur rating can go down in some time.

This can also happen in the rare case that a game gets its base Steam price reduced.

Thanks for the answers, guess it's time for a new giveaway! ^^
Going to put up my first non-bundle giveaway!

It's frustrating but unavoidable. CV gets corrected in retrospect so the only guarantee that you have is that this was not the last time this happened.

The only way to avoid losing a level is to always be a bit ahead of your current level. I've been stuck in 7.2 for a good while now, managed to get to 7.22 for a little bit before being brought back to 7.2

https://www.steamgifts.com/discussion/eikjy/unspoken-rulestips-of-steam-gifts this may help

You see, maybe, something at https://www.steamgifts.com/bundle-games or https://www.sgtools.info/lastbundled . Useable for each one.

Or https://www.sgtools.info/sent/Madpie24 that show only your stuff.

Yes, this unfortunately happens... I got back from 8 to 7 a couple months ago and was just as surprised as you... If the graph of levels would show retrospectively, that would be amazing btw...

If the full price of a game gets permanently lowered on Steam, you will also lose the difference in CV. Even when the game doesn't get bundled or given away.