How do you fix the issue and reconnect to Sonarr?
Are you needing to restart Sonarr or the browser?
It looks like either Sonarr is no longer running or a firewall is blocking the connection (but it’s on localhost so that can probably be ruled out).
You logs are a couple weeks old, but this is a huge gap of time, that can’t be explained by Sonarr restarting:
2022-04-08 12:01:15.2|Debug|Api|[GET] /api/v3/config/host: 200.OK (10 ms)
2022-04-14 14:32:33.2|Debug|SabnzbdProxy|Url: http://localhost:8080/api?mode=get_config&apikey=(removed)&output=json
Because debug logs would have start up messages.