anyone else have this issue

you play like a completely different player in customs/tournament style games compared to ranked. in customs i play w friends/collegiate players that are serious i go nuclear often dropping like 25+ kills as initiator/smokes, but when i play ranked my brain just shuts off and suddenly i cant aim.

Well in customs you always get more comms, have more orientation, utility is structured and you actually have some sort of team cohesion

Yeah it's the same for me, I believe it's because you can get used to ranked being a coin toss as far as what your team will be like (skill, comms, etc.), so you might be subconsciously putting less focus on the game itself. For me, it's just not enjoyable to be on a team with no comms and/or teamplay, which is like 80% of ranked games, so I even find myself sometimes doing braindead shit because i'm not mentally invested in the match.

both have very different environments

i cant explain it but normally in ranked you tend to have more 1v1s and it is more "unexpected' i dont know to say it but it is more demanding in term of aim i guess ,

Other way around for me I go crazy in ranked I go try playing 10-mans I bottom frag so hard :(

when i was a player for Vault IX, which was a really good diamond/ascendand team (i still am but we dont really play anymore),
i didnt really drop anything crazy, (never more than 24) with astra and omen, the enviroment was really cool and i played completely different from ranked

It's going to sound weird but I argue it's due to the difference in the pressure you feel.

I played a few collegiate games but my team was nothing serious. Our highest-ranked player was immo1 at the time (imm2 now i think) and we were facing teams that had multiple radiants, so we obviously weren't expected to play well and just tried to have fun. My diamond ass would sometimes go crazy against these immortals though, which I know wouldn't happen in ranked. We'd obviously never win, but I'd have my moments. I have a clip somewhere in a Discord server with me 1v4 clutching post-plant against one of the top-ranked teams (we lost the map 13-2)

In customs with friends (10mans) I usually instalock a character I really want to play and try to play them in a silly way. I never touch Yoru in ranked but I always play Yoru in customs because I want to cheese and annoy my friends.

if you play ranked (soloq, stacking, whatever), there's something you can lose -- your RR. in customs or tournament play, assuming it's not a SERIOUS serious tournament with big money on the line and you having an actual shot of winning, you don't have anything to lose, really. so, you don't feel that same amount of pressure IMO.