Hi
As you have discovered, when a new feature is introduced it is sometimes available and sometimes not. Your experiment covers a lot of ground. If you want to pay close attention to the various builds, look at the number following the version number. For example, in your most recent screen shot you have version 16.64 (2208141)
The number in parentheses is the date. In your example, August 14, 2022 build 1.
16.64 current channel builds delivered by Microsoft servers and Apple servers are slightly different. Builds delivered by the Apple store can not be used to join the beta channel.
You could easily have multiple machines all with the exact same beta channel build, but each presenting a different combination of features. Microsoft uses control groups to compare behavior of various things they're testing at any given moment. Microsoft wants feedback from beta testers using the Help menu's Feedback options. The feedback should be about the specific build and Mac on which the report is being made.
Questions and comments about the beta channel should be made in the special forum for beta channel users:
https://answers.microsoft.com/en-us/officeinsider/forum
The forum we're in right now is reserved for topics on the general release current channel builds.