Constant request of Acme Challenge file on Appengine from Google-CodePudding

I am working on an AppEngine app that hasn't gone live yet(i.e. accessible online, but no users other than myself). I tried using let's encrypt SSL before switching to Google Managed SSL. After removing Let's encrypt SSL, my app is constantly getting a request from Google to the acme challenge file and they are all marked as WARNING. These are several samples of such entry (some text are replaced with dashes):

 - 2001:4860:4801:2045::4 - - [15/Sep/2021:17:49:24 -0700] GET /.well-known/acme-challenge/-------------------------SOk HTTP/1.1 404 - - "Google-Firebase" "-----.com" ms=1 cpu_ms=0 cpm_usd=0 loading_request=0 instance=- app_engine_release=1.9.71 trace_id=-
 - 2001:4860:4801:202c::1b - - [15/Sep/2021:17:34:24 -0700] GET /.well-known/acme-challenge/-------------------------SOk HTTP/1.1 404 - - "Google-Firebase" "-----.com" ms=0 cpu_ms=0 cpm_usd=0 loading_request=0 instance=- app_engine_release=1.9.71 trace_id=-

I'm getting 8 request every 15 minutes, and they all results in 404. How do I stop this? I have removed the SSL and the challenge reference from my app.yaml file and have also deleted the actual challenge file. I am not using any load balancer as mentioned in this post. I'm concerned because it is costing me $5 in the last 1 week.

CodePudding user response：

thank you @MabelA. Reconfiguring the custom domain (deleting and readding) seems to solve the problem