Audit succesfull logons , loging every 2 seconds
I feel like this is normalish behavior but can't find any information on why. The most I see is that Microsoft's docs state that specification also logs connection reuse from the connection pool:
Events in this class are raised by new connections or by connections that are reused from a connection pool.

It does seem to be a common issue for people trying to audit logins in the same sense as you are, e.g. this Reddit post.
You may want to try Tony Hinkle's accepted answer on this StackOverflow as a workaround and see if you stop getting redundant logs in your audit. (The drawback with this solution is you have to specify each Login name you want to audit, but maybe this is a plus depending on your end goal.)