I found a bug with character selection If you have more than one of the same character rostered.
Specifically, in my situation:
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I was going through the easier nodes with a team consisting of my 1/2/0 Thano5 and 2 ‘cannon fodder’ characters
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The cannon fodder happened to consist of my level 40 Juggernaut and level 70 1/0/0 C4rol
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After winning the match I started a new match, skipping through the character selection screens quickly
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During the new match I noticed my C4rol had been replaced by my level 200 5/5/2 one!
I think the game incorrectly selects the highest leveled one when restoring the previous team.