Since a few days, LR 9.2.1 tells me upon startup that a new version is available. Of course, this is wrong. Using the Help | Updates menu has no effect. Adobe CC Desktop says : up to date.
Also happened to me immediately after upgrading to 9.2.1 on one Windows machine, but not another. Like Rikk, it was one and done for me and hasn't come back. Both machines are Win10 1909.
I see the spurious update alert whenever I switch Preferences > General > Language (at least for English, German, French, and Italian). That's not something the typical user would do, of course, but maybe it will give a clue to the developers.
Signing out and back in via the Creative Cloud desktop app didn't change the behavior.