Is the google cloud sql v1beta4 api endpoint still in beta? Or did they keep this name for compatibility... because otherwise ur would mean that it's not fit for production use.
The Cloud SQL API is flagged as still in beta. See:
https://cloud.google.com/sql/docs/mysql/admin-api/
What the beta tag means is documented here:
https://cloud.google.com/products/#product-launch-stages
and says:
At beta, products or features are ready for broader customer testing and use. Betas are often publicly announced. There are no SLAs or technical support obligations in a beta release unless otherwise specified in product terms or the terms of a particular beta program. The average beta phase lasts about six months.
As for not being fit for production usage ... while true that there is no support and no SLAs, there are many times where using beta code may still be of benefit. For example, if I can perform a task today that is complex and takes a long time manually but have a new API that is beta that does it quickly, I might be prepared to use the beta API with a backup of using the older way if something goes wrong.