frigging b*tch ahh map crash

so ive been playing codm for over 6-7 years and my level is 280 and my rank last season was legendary
this fuckass season of honkai impact , every mp match i play in crash is like this i win one and then i lose one and sometimes its fucking twice or thrice that i lose , and to players with 20 to 60 or 100 less players with m4 and lmgs like rpd , even if i use the bal-27 and am fairly good at it but like man
this has happened too much too much to be a coincidence or a matter of skill
one match i dominate with 90+ rating the next match i know , mine is 60 or 50 so,

and it always happens at crash , i dont play ranked and before this bitchahh update i could win 5 matches consecutively and now im stuck in this and it is really frustrating

if you can recommend some good mp guns so please do so