I mean that's always a possibility
100% of people won't like you 100% of the time
just ignore it and move on
or if you feel they really have a point, do your best to change, and then move on
overall I guess just don't let it bother you
if they aren't brave enough to say it to your face then it isn't worth your time
And keep track of who does that. If they talk bad about someone to you, odds are they'll talk about you to someone else. And those aren't the kinds of people you need to keep in your life.