Adding more to above points:
Also, you may configure the health check options by configuring the app settings WEBSITE_HEALTHCHECK_MAXPINGFAILURES
and set value to 2-10
This is the required number of failed requests for an instance to be deemed unhealthy and removed from the load balancer. For example, when set to 2, your instances will be removed after 2 failed pings. (Default value is 10)
Further you may want to know that Load Balancing is the used to Configure the time that an unhealthy instance remains in the load balancer before it is removed.
Suggest you to refer to this document for more details on health check https://learn.microsoft.com/en-us/azure/app-service/monitor-instances-health-check
Let us know if further query.