I found following article. and we think we are running into same issue. We are running sssd with RHEL 7.9. I have following questions - 

1. Is this issue fixed with RHEL 7.9 ?  
2. Is it possible to disable periodic run of purge. We basically dont want to purge in favor of performance improvement. 
3. If so what is the downside of it. 
4. How do I verify is this is impacting us. I see very high cpu every 3 hours. I thought this may be the cause. 

1430415 – ldap_purge_cache_timeout in RHEL7.3 invalidate most of the entries once the cleanup task kicks in

Sanjay Agrawal