Filebeat no releasing deleted files

Enabled debug logging for harvester on one of the machines. I noticed that Filebeat is quite busy discarding log lines as for these logs I only want WARN and CRITICAL. over 95% of all lines are discarded, probably over 99%. These logs are quite busy. I noticed that Filebeat logs are now rotated out after about a minute, so not sure how much useful information I will be able to capture...