The same thing happened 2 years ago. I wouldn't read anything into that.
Just because a line on the tracker ends, that does not mean the work is done, it's ready for launch, or it has even been worked on at all.
For example, two years ago lines for 31 chapters completed, as did the Retaliator Gold Standard, work on the Liberator, and the Boreal Stalker. Except for the Liberator, which finished in September, they all finished in May through July.
Where is the Liberator?
The Retaliator Gold Standard?
Squadron 42?
They were worked on but aren't finished.
The point being made wasn't centered around the work finishing, but rather that nothing new is being added\extended... Something ending on the tracker only means they have stopped working on that (complete or not) and have moved focus to something else, but with regards to Squadron 42, there is nothing else being added for those teams to work on outside of "bug fixing", "tech debt", "misc support" or the Polaris.
The only reason that the various teams have nothing on the tracker for Squadron 42 would be either there is nothing left to be worked on, or there is something blocking their ability to work on an area. With Squadron 42 being CIG's main focus, this would logically imply that unless there is something in one of those remaining areas being worked on which is blocking work on any and all other areas of the project, there is nothing left to be worked on.
It's quite possible that there is some "tech debt"\"bug fixing" required for further work on existing "finished" lines on the tracker (much as tech required for the Hull C was also needed to allow modularity in ships - retaliator, for example), but if so, it's unusual to see that they haven't been able to clear whatever is blocking even a single area of Squadron 42 that is preventing staff commencing\returning to working on an area of the project...
With regards to your "where are they examples" where work ceased in the past:
For the Retaliator, if you look at the team assigned (EUVC) at the end of the "allocated time", they went from that to working on the Spartan.
For the Liberator, if you look at the teams assigned (VCA and Narrative), you would be aware that it was only concepting work and providing the ship a "background"\story that was worked on. The last team working on it (Narrative) then appear to have moved to either zero G push\pull, or to working on 4 Squadron 42 chapters that work returned to at that time.
If go to the "teams" view on the tracker, not a single "sq42" team has a deliverable being worked on (The last finished at the start of the month)...
What I am highlighting is that the more time that goes by with nothing being added to the progress tracker regarding Squadron 42, the more it looks like there is nothing remaining to be worked on for the project and so it is nearing completion.