GFork

I made this script to block groups you've specified in the code on Mangadex's latest releases (look in the code to add more groups).
This only checks the first chapter so it may hide unintended entries.
If it sometimes doesn't work, try refreshing.
This by default removes "Azuki Manga", "Bilibili Comics", "Comikey", and "MangaPlus" as an example and the comments describe how to add more.
I don't know if updating will delete your groups so try creating a backup of the groups but I will try not to update unless it breaks.
I have only tested on Violentmonkey and Chrome so YMMV.
Check out my other script to darken read chapters in latest/follows.
If you have any comments/questions/bugs leave a comment and I may be able to help if you need it.