The whole thing is a black box. I’m sure someone on some Android forum has figured it out.
I guess it is not so difficult. There is the Google Playstore app that updates as other apps even if it is transparent for the user.
And you you the underlying layer of the Google play services that do not correspond to the app directly. And this service layer is updated from the settings menu. Unfortunately there is only a date of the patch level mentioned. But since I received an update almost every day in the past days/week (today there was another update) all based on the same patch level this date does not change and there is no version numbering visible for those updates. The patch level date is currently Jan 1st 2024