If you chart it, I imagine it was a downward trend even from the start, but it wasn't until when the wait for Elis began in ~2020 that the update pace really started to decline and the instance of scatterbrained content additions in Dominion started ramping up. As of last year with Elis done, it then morphed into "no updates or announcements for 6+ months if I'm feeling too bad" after a few periods of indefinite delays starting in late 2021 - early 2022.
Right now, I think the phase we're in is is that Innoxia has one relatively large patch that she plans, but only develops bits and pieces of it whenever she feels like it. Then, she bunches a few of of the completed bits of her checklist, beaking them up into smaller patches, which she staggers the release of to "chain" updates over the course of a couple weeks. She then works on the next big patch, repeat ad infinitium.
This I think explains this little micro-pattern we've seen the past few patches: the expected long waits, and then the series of smaller additions following a patch release before they suddenly stop.