This particular issue didn't appear until this update here: https://legacy.curseforge.com/minecraft/mc-mods/beast-slayer/files/5900271

I've found Giants in the Nether, in the End (as of recently), and even in the Erebus all over the Elysian Fields biome.
Any modded biome that is considered a plains or savanna biome seems to attract these guys, even in dimensions where zombies don't exist. For the Overworld that's not a problem, but in other dimensions it doesn't always make sense for them to be there.

One suggestion I have would be to create a whitelist of dimensions where mobs from this mod can spawn. I've noticed that Frostwalkers can spawn in the Twilight Forest dimension too, but thankfully the way they spawn doesn't break the immersion of that mod.

Any chance this bug can be fixed?

Thank you!
NorfriedTheVikingWarrior