Impossible for anyone to know.
Did you read the error?
It tells you to check console for errors.
So, check the console for errors and upload the whole logs/latest.log to pastebin

If you are a server admin, please check the console for any errors

You should really learn to read console logs

I'd have to agree , The latest builds are not right . If a player logs off while in the air , they get kicked when logging back on , contrary to setting allow flight in survival . I just became aware of this . I think it started with last weeks builds . When I have time I can look into it some more.

[16:45:35] [Server thread/WARN]: maelnelson was kicked for floating too long!
[16:45:35] [Server thread/INFO]: maelnelson lost connection: Flying is not enabled

@Tsoccerguy3 How is that a LuckPerms issue?