Hi,
Application Insights has detected that the performance of your application has degraded.
The notifications include diagnostic information
Microsoft offers a path that helps diagnose de issue:
https://learn.microsoft.com/en-us/azure/azure-monitor/app/proactive-performance-diagnostics
You should also look at Profiler:
https://learn.microsoft.com/en-us/azure/azure-monitor/app/profiler-overview