Do you play Mystery Heroes a lot? I spend my weeknights playing Mystery for the loot boxes. Then on the weekend, I notice my endorsement drops to 3. Then I get back up to 4 within a few games of quickplay. I suspect if I stopped playing Mystery heroes and only played Quickplay, I'd get up to 5.

I make sure to gg or ggwp after every match or gr after every round even if I'm feeling a bit salty. Writting it always diffuses the salt. Some people reward competency (cards). Many people with mics endorse others with mics. I communicate as much as I can and congratulate people when they make good plays/decisions. I never criticize because I don't know the whole story. Hard to judge others decision in those few seconds waiting to respawn. You don't know what brought them to that moment.