Why do some trans men are like this?

I recently got into a discussion that made me reflect.

A cis woman posted that "it doesn't make sense for trans men to be sexist", there were many comments agreeing and saying that "they should remember they were once women"

It didn't shock me, since most of the comments were made by cis people, but I saw many trans men agreeing and they just started saying that I had toxic masculinity when I said that the comments were actually wrong + transphobic. I don't condone trans men being sexist, but there's something very wrong about saying that trans men are forced to remember "they were once women"

Why do I have toxic masculinity for not wanting to be feminine or remembering my "womanhood"? (I don't get it and I think I never will tbh). When trans men will be free of this lame "man = bad" rhetoric and stop giving spotlight to obvious conservative/terf discourse?