Somebody send bots to my server
in mysql i have 5000 players data
https://ctrlv.cz/nYoe
Is it possible to add an account after logging in? (when by on lobby servers)
I use captcha robots will not register

maybe you should look into why your server got bots attack. My guess its an online-mode: false type of server?

Also, default group players shouldn't be stored in database iirc, unless you have a online-mode: false server and plugins altering UUID? see: https://github.com/lucko/LuckPerms/wiki/Default-Groups#where-to-start