I am having the same issue. My apps with database connections to Google Cloud Platform are not able to connect to the databases. I have all shinyapps IP addresses whitelisted per the documentation 3.8.4 of the shinyapps user guide
Perhaps shinyapps added a new IP that needs to be whitelisted??
The apps were able to connect to the GCP databases while running on Shinyapps this morning, but just recently they can no longer connect. I can connect to the GCP database just fine from my local computer.