I rarely have issues, but occasionally I see errors like these:

All rss-capable indexers are temporarily unavailable due to recent indexer errors	
Indexers unavailable due to failures: The Pirate Bay (Prowlarr)	
All search-capable indexers are temporarily unavailable due to recent indexer errors	
Indexers unavailable due to failures for more than 6 hours: RuTracker.RU (Prowlarr)

Digging into the logs

Warn|Torznab|API Request Limit reached for The Pirate Bay (Prowlarr). Disabled for 00:00:59

|Warn|Torznab|API Request Limit reached for RuTracker.RU (Prowlarr). Disabled for 00:00:58

I set the query and grab limit to 10 an hour for those two indexers, based on the advice in the other thread