For context I played in Season 0 and 1 on PC, and 5 on Xbox. I know the devs are working hard to make this game better, but the game is getting frustrating and becoming less enjoyable.
To start, SBMM is an absolute nightmare for players like me. I'm a level 69 with a 0.94 k/d, which isn't great. However, the matchmaking put me in with 3 predator squads today and many, many more level 400+. It's not fair for those of us who are ok at this game to be free kills for skilled and experienced people. If I'm a level 69 with a 0.94 k/d, I should be matchmaked with anyone from level 50-150 with roughly similar k/ds, from 0.7-1.1. I know it is hard to do this, but it would be better for the game in general.
More than the SBMM itself, some players are frustrating to play with as well. This isn't a generalization, I'd say most are fine, but the few can ruin your day. For a team-based game, the teamwork isn't there. I think in all modes, respawns and revives need to receive more credit and points. If you revive someone in ranked, you should get like 5 points and 10 for respawn. This would encourage ranked players to play with their team. In pubs, make the xp higher to reward team players more. This is what the devs could do in order to make this community less toxic.
Regardless, I enjoy this game more than most and I just want this game to thrive. I appreciate all the work Respawn does, but changes like this can exponentially improve the game as a whole.