No, this issue is caused by the latest versions of Watch Face Studio, not by Google Play.
And we don’t need to contact the Google Play team for this.
If you create a watch face using WFS 1.7.9, the “Set” option appears when installing a new watch face.
However, if you create a watch face with WFS 1.7.13 or later, only the “Uninstall / Refund” option is shown—just like it was in the oldest versions.
I had already reported this almost a year ago, but as usual, it was completely ignored.
We also discussed it here recently:
The Watch Face Studio team should kindly consider providing a quick fix on their end.