I have a app service plan running an drupal docker image, with 4 mounted file shares trough Path mappings on the app service: (https://docs.microsoft.com/en-us/azure/app-service/configure-connect-to-azure-storage?pivots=container-linux)
/var/www/html/modules
/var/www/html/sites
/var/www/html/profiles
/var/www/html/themes
Since 2 weeks now, there is a constant stream of attempts to open, read and close the file __lastCheckTime.txt on all 4 shares. Creating around 200 calls/minute, costing about half my total running cost of the file share + app service + mysql database. Azure file cost wend up from 30 cent/month to 30 cent/day.
There is nothing in the docker image that would call __lastCheckTime.txt and the only other place i've ever seen the file is in the /LogFiles folder on the sftp of the app service.