i believe you had no malintention with this. art is tricky, and basically using things directly from other people counts as art theft.
borrowing palettes and looking at a flower for reference, or looking at an art with sparkly anime eyes for reference, is normally alright. but copy+pasting art is where the line gets crossed : ( usually permission has to be given, or you have to buy the rights to something in order to use it directly.
inspiration + reference is alright (and in this case, using the models from ingame is okay too since the rules said its okay) but you have to be wary of crossing the line.
people may still be cruel to you after this becauseā¦ idk, internet i guess, but im very glad you learned and apologize. thats the important part in my opinion