Crash Log
Happens on MC 1.15.2 with only fabric-carpet 1.3.27 installed on both my server and client, after updating from carpet 1.3.25.

Client crashes whenever I jump. Flying around in spectator/creator mode does not cause the crash. When connecting to the same server using a client without carpet installed, the crash does not occur.

After deleting my playerdata on the server world, the crashes stop happening. Running the world on singleplayer also does not cause any crashes. Running carpet 1.3.25 on both client and server also did not cause any crashes.

After deleting my playerdata on the server world, the crashes stop happening

Do you have a backup of said playerdata that you can share? Something may be corrupt there.

yeah, that would be helpful. otherwise I can't replicate that

or a world download - even better

I too had this happen, although for me it seemed to only happen while wearing an elytra, and then jumping.

I know what you all had in common - enabled antiCheatDisabled rule. Will fix - obvious bug