Invalid anti-cheat message

Platform: Steam

For the past two weeks, I've been kicked out of games (around every 10-15th game I'd guess) followed by a "The client sent an invalid anti-cheat message" error message.

In the games leading up to the error (maybe 1-2 games before), and in the game where the error occurs, I've experienced delayed audio and other weird bugs, such as my guns being invisible for a brief time and no animations when dropping out of a dropship upon respawn. These bugs persist even when the game is closed and reopened.

I've attempted to run any anti-cheat files and Apex Legends itself as admin. This issue has, however, not been resolved.

The game doesn't enable you to reconnect to the match and punishes you with a 10-minute penalty and an RP penalty if you're playing ranked.