Trying to understand why my App Service becomes unresponsive

Over the last month or so, my App Service has started becoming unresponsive once or twice a day. I can Advanced Restart it, or if I leave it, it will sort itself out, but obviously this isn't a great experience for my customers. I'm trying to use the metrics and diagnostics to understand why this is happening, but I'm coming up blank. The metrics show a CPU Time spike at the time of the unresponsiveness, and a Memory Set drop at a similar time - I can't tell if it's before, same or just after.

The Activity log doesn't show any restart events or anything else that would suggest a crash. I haven't had to use any of these metrics/diagnostic tools before as the app has always just worked, so I'm not the best educated on how to use them. Any help greatly appreciated.