Bad login data errors in syslog

I see the logs below in syslog every 7 seconds. There is only graphite-carbon, graphite-api and grafana-server (v8.4.3) on the server (Ubuntu 20.04). What could be the problem ? Is there a process inside grafana trying to login ?

Mar 9 17:58:20 zurafa grafana-server[19323]: logger=context t=2022-03-09T17:58:20.35+0100 lvl=eror msg=“bad login data” error=“bad content type” remote_addr=127.0.0.1
Mar 9 17:58:20 zurafa grafana-server[19323]: logger=context t=2022-03-09T17:58:20.35+0100 lvl=info msg=“Request Completed” method=POST path=/login status=400 remote_addr=127.0.0.1 time_ms=0 size=28 referer=

Hi
I have a similar situation only on the grafana server where I have installed graphite-carbon and graphite-api.

Probably this is connected with "bad login data" instead of "Logged In" at /login after upgrade to 8.3.6 · Issue #45198 · grafana/grafana · GitHub

This error is definitely made by the carbon-cache process.