Way back in 2016 or so Apple fixed slow Camera launch with a Camera-specific scheme.
The basic idea (to simplify) is that instead of having a unified pool of free pages available to all apps, we have two pools, a pool of "really" free pages, and a pool of pages that are relevant to the execution of the camera app. Under normal circumstances we only need pages from the "really" free pool, and we only tackle the "camera" pool when things get bad.
This solves the fast camera launch problem but is not optimal in another way; it does mean that, overall, apps may run a little slower because they may be using less memory than they could.
It's possible that what we are seeing is a bug.
Or it's possible that a deliberate decision was made that it was now time to end this special case situation for the Camera, and that the slight slowdown was acceptable. Normally it shouldn't be too bad because most of the pages are part of general shared iOS libraries that will be present anyway. Perhaps this situation occurs in cases like large games that take over the entire phone and mostly use their libraries for everything, not Apple libraries, so any subsequent app launch (Camera or otherwise) seems slower than normal?
(One way to improve things may be to retain the special pool, but make it limited more to common Apple libraries and less about specifically the Camera app?)