I think it’s more clear if you put it in brackets. This is usually how posts are tagged from what I’ve seen.

Like this: [META]

Do they always ask for the same characters? I’d imagine they could hash the password as well as saving only the 2nd and 9th characters as plaintext. Still a bit of a security risk but not nearly as bad

You could try finding an instance that isn’t porn-friendly. The one I’m currently using (https://dmv.social) asks users not to subscribe to any NSFW communities, which prevents those communities from showing up in my All feed.

You should look into Kanata. It lets you remap the whole keyboard, same idea as QMK, except it’s running on your computer instead of the keyboard itself.

It can be a bit tricky to set up if you’re not used to that sort of thing, but I managed to figure it out so if you have any questions feel free to ask.