Different Maximum server memory across Availability Replicas
That’s due to fact it (SECONDARY) has to serve same level of work load as PRIMARY. I.e. when PRIMARY is memory intensive for 32GB, and SECONDARY limits to 24GB in the incident when it’s become PRIMARY it could perform same as primary the impact (8GB Memory) could be in various factors


Additional connections might not established 
Existing requests might be slower 
Log redo could be backlogged 
Etc..