SCAN Listener.logs excessive logging

We generate several tens of gigs daily on our system, and ours is not even a large cluster of database.

The listener log (log.xml) is full of such entries (some entries replaced, for data protection reasons)

<<quote>

<msg time='2021-06-23T17:15:10.184+02:00' org_id='oracle' comp_id='tnslsnr'

 type='UNKNOWN' level='16' host_id='<hostname>'

 host_addr='<IP>' pid='378993'>

 <txt>23-JUN-2021 17:15:10 * (CONNECT_DATA=(SERVICE_NAME=<SERVICE_NAME>)(CID=(PROGRAM=test)(HOST=<hostname>)(USER=test))) * (ADDRESS=(PROTOCOL=tcp)(HOST=<IP>)(PORT=<port>)) * establish * <SERVICE_NAME> * 0

 </txt>

</msg>

<</quote>>

My question is, why does it say level 16 and is there a way to generate less verbose output?