Neither Mozilla nor the Firefox web browsers has anything to do with the Mobile Legends: Bang Bang game. You will need to contact the support for this game and according to https://www.reddit.com/r/MobileLegendsGame/comments/1eem1tz/how_does_one_contact_mlbb_support/ you contact support through the game. hmm. Being a Chinese game may make it harder to get support compared to games made in other places.