Doing a little extra is good. Doing everyone’s work just so you can complain about it isn’t.

Extra effort and resentful overwork are not the same thing. Taking on a bit more makes you useful and teaches you the job, while absorbing everybody else’s work so you can carry it around as a grievance helps nobody, because the complaining cancels out whatever the help was worth. It also stops other people learning their share. Generosity with a ledger attached is not generosity.

If you are doing somebody else’s work, either stop doing it or stop mentioning it. Hand it back plainly, or take it on and let it go. Resentment usually means you agreed to something you did not want.