I would tend to agree with you in that I am pretty sure CIG has, for a while already, invested a larger portion of its human resources into SQ42, and that will inevitably impact the PU patches content, no doubt. The thing is, that rational is underpinned by an expectation of a SQ42 release sooner rather than later, otherwise the argument of technical limitations and management incompetence for the slow down would still be the most logical one.
So, do you mean CIG was just padding their release view with useless clutter that were later withdrawn?
I am shocked, shocked I tell you!
Either way, even if you remove performance optimization from the patches it showed up (2018-2020 period) the overall trend remains largely exactly the same for that category: 8(2018), 13(2019), 4(2020), 1(2021), 1(2022).
Sadly, that is not really a very consoling argument in this discussion. As mentioned, one of the reasons for progress slowing down to a crawl is precisely technical limitations in CIG´s engine and code. But that is by the by, there are still 7 categories more, Characters, AI, Gameplay, Ship, Vehicles, Weapon items and Core Tech, where CIG´s actual delivery track record has come to a halt as well and for which you would need to find additional rationalisations.