More info about this bug. So to reproduce it you need to play in creative for about 15-20 minutes and constantly build and edit with pickaxe.After this fps start drops(on the down arrow)if you using sprint and tap it fast,switching between combat and build mode and editing any build fast.Usually I play with 90 fps and 0 3d res. Also this happens for me on this map 0550-1651-3094.Than more you play the worse it gets.In BR it happens after a few games.Also this bug started after 17.20 update(video proof from another guy https://reddit.com/r/FortNiteMobile/s/dBQr3TbPEh)
Thanks. We still have been unable to reproduce this and we haven't been receiving reports about this one (aside from your reports). It definitely appears it could be device-specific and a low repro but we still have this logged.