A lot of us do, I think that it’s normal as long as we work on keeping our mean thoughts inside rather than executing them irl, just like when most people have mean thoughts about anything else. It’s (mostly) normal, depending on the thought, but how you react to it is what determines your morality.
Many do, but it’s not the end of the world! It’s good you’re recognising it, because that’s the first step in addressing it! It can be good to catch the thoughts, “document” them (whether just mentally or if you want to write them down), and work on identifying where it comes from and addressing the source. A lot of mine comes from a lot of misogynistic tropes that I picked up from media that I’m still learning about and unlearning. Some of it from depression and my issues with self-worth.
I like to write things down a lot and sometimes I’ll catch a thought of “wow, that’s not right. Wait… why am I thinking that? Where did that come from?” and then I try to figure out what thoughts come from that, and where those may be from. Sometimes I’ll compare my thought to a comment my mom or sister has made about themselves in their insecurities, or identify it as a stereotype or a “beauty standard” setup by others. Just as an example! There’s no firm “right” or “wrong” in navigating it.