If cache_full is true and a restart is neither pending nor in progress, that probably means that the waste is not high enough to exceed the max waste percentage.
You can check by comparing current_wasted_percentage with the INI variable opcache.max_wasted_percentage. In this case also the cache hit rate opcache_hit_rate will drop below >=99%.
Solution: Increase opcache.memory_consumption setting.
If cache_full is true and num_cached_keys equals max_cached_keys then you have too many files. When there is not enough waste, no restart will be triggered. As a result there are scripts that don't get cached, even though there might be memory available.
Solution: Increase opcache.max_accelerated_files setting.
If your cache is never full, but you are still seeing a lot of restarts, that can happen when you have too much waste or configured the max waste percentage too low.
Solution: Increase opcache.max_waste_percentage setting.
https://tideways.com/profiler/blog/fine-tune-your-opcache-configuration-to-avoid-caching-suprises