There are so many backseat gamers and armchair analysts queuing that every single thing that a teammate or I do gets called out.

Pick an agent you want to play (unrated) and people start saying stuff like "Why did you instalock x?", "x other agent would have been better", "x agent is useless should have picked sage instead".

Teammates die, spectate someone and constantly instruct them what to do.

Pick something like sage or omen and do something other than the default with your wall/smoke and people tell you that you should have walled mid or smoked main.

You're in a 1v2 or 1v1? Your teammates wont keep quiet and either fight amongst themselves or tell you what to do.

Understand that (atleast in lower elos) people aren't going to be perfect. You don't need to keep handing out advice because you're also in the same skill bracket as your teammates (if you think otherwise, just kill the enemy team instead of focusing on your teammates' mistakes). A lot of us just play this game a couple hours a day after work/college for fun and have no intention to improve. I've stopped playing ranked completely but even in unrated people still make a job out of the game.

Not sure if this is an issue for everyone. I play unrated in Mumbai and Singapore servers and my skill level is around gold.