If possible for you, I’d say to approach the person and ask for them to credit/remove said pictures. I personally like to give some benefit of the doubt if a person technically isn’t claiming that they drew it themselves, so I try to approach them first and ask to remove.

If they deny it or simply don’t comply, I’d think to simply report it. Be sure to source your images and where they were originally posted at that! Having clear and thorough evidence does help!

(This is also why I’m sure to sign my work as well, more so in spots where one may not realize it’s even there, let alone where it would be difficult for one to try and remove.)

It’s understandable if it’s hard to deal with this and not be harsh at the same time. Honestly, it’s natural that anyone would get mad or upset if this sort of thing occurred with anything they’ve created. But overall, I personally try to go the calmer route with these sort of things. (Though this is fairly new to me, since I haven’t really experienced this use/theft of my art so frequently since I started drawing FNAF stuff, so I probably I’m probably not doing it the way anyone else may do it. <:X)