I have noticed that you can lose endorsement level in arcade modes that you cant gain endorsements from (Mystery Heroes for example), AKA for leaving games. If they call it a “non serious mode” that you cant gain endorsements from, then you shouldn’t be able to lose them either, unless its from someone reporting you.
I also heard that it decays over time…It would suck if i got punished for playing a lot of arcade and lost endorsements simply because of that
maybe someone reported you
are you sure it was something like mystery heroes though?
I’m pretty sure there are some arcade modes where you can endorse people so normal endorsement rules would apply there I think
Any time i have dropped in endorsement level, it was after leaving a mystery game (which i play the most). I even experimented when i gained level 3, dropped down to 2 after leaving a few games on purpose (for the test).
I think if anyone mainly plays a mode where you cant gain endorsements, leaving games (frequently or rarely) will eventually lose you your endorsements because you cant gain them in said mode.