Can I filter out hentai games from showing up here on SG?

I don't think there is a general category filter (unless the custom SG script has one). I just hide them as I find them, and they eventually run out. ;)

On the giveaway page, there is an eye with a line through it that will hide the game when you click on it.

No.

The question came around 6 times up in the last 3 years. Strange that nothing was found from you in the discussions.

Sadly, you can't. You're destined to play whack-a-mole for eternity. You can only filter them out individually (the eye icon).

What I do is check only for wish-listed giveaways, and I use ESGST to hide featured and pinned giveaways.
https://www.steamgifts.com/giveaways/search?type=wishlist

If you need ideas which games to add to wish-list, you could try this:
https://www.steamgifts.com/giveaways/wishlist

I would really love this too. I tried using ESGST's game tag filter, but it doesn't seem to work for the user-defined tags such as 'Nudity', 'Hentai', 'Sexual Content', etc. 😢

Thank you everybody. This is a bummer, but oh well 🤷‍♂️