Using a client that shows the pronouns in hexbear is good and it sounds like you are doing that now.

As a follow up, I recommend approaching gender just as one would if they were bring mindful with new people. If you don't know pronouns, using they/them is a fine way to start referring to someone neutrally. You can also just use their name. It is considerate to then figure out what they prefer in a non-awkward way, either by how others talk or by just asking them nicely. Having pronouns displayed by names is just helpful for clarity and speeding things up online.

when unsure or lazy i use they/them

Its an honest mistake and I think if you appealed the ban you'd have a good case for it, however as you now know that's the trans flag you can be more mindful in future :)

i would block all those people and move forward with my life

Sometimes moderation is ridiculous. More “zealous” moderation teams just strike everyone relentlessly. Usually the kind of people that make boomers label every young people as snowflakes

Back when I was on Reddit, on the LTT subreddit, I started reading rumours that formerly known as Anthony (I am here meming with the whole X ordeal), had transitioned into Emily, and I checked the website sorta confused. I thought it was just a mistake or a joke until I saw it actually confirmed. So I did that whole party meme with me at the corner not realising that he had transitioned into she, and everyone else already having congratulated her. This got me banned.

No, it shouldn't necessarily be an expectation to check. However, if you don't then I think it's a reasonable expectation to not gender someone one way or another unless you do know or are corrected, using they/them and other neutral ways of referring to someone like person etc is the best idea if you can't or don't feel up to checking.

I just checked the apps I use, and sync shows display names properly.

I uh, I don’t think it’s reasonable to expect people to check others profiles to ensure we are correctly pronouning them

And yet, in that little whine right there, you managed to use the very gender neutral pronoun that would have saved you all this hassle (including the hassle you're making up of having to go and look up the pronouns of every individual you interact with).

So you know it exists, and you know how to use it, but you decided to try and be funny instead, and it backfired.

You misgendered someone, and now have to deal with the most minor of minorest consequences for harm you caused to another.

You are still free to create 100 different accounts on 100 different instances, just not the one where you broke the rules. No one owes you a platform, deal with it.

Your choice now is to double down and make it worse, or you can be an adult, admit you made a mistake, and learn from it for the future so you don't repeat it.

I dare to say you have already chosen, but feel free to prove me wrong.