From the beginning, it seems, graphics are unsuitable for solving the basic task of monitoring the state of an application ant its changes.

A software which it is interesting to survey in a way either has a logging functionality which serves the purpose or should have one. Increasing the technology-stack to do something as simple as that has been the trend for too long and it has driven us into a mess. I actively oppose the use of a screen recorder in this context.

Which brings us full circle with posts made half a year ago, eg in this thread:

This is not a basic task. And this is not a simple issue (as you can see). X - and I think it is valid on MS Windows too - will draw only what is really visible. Processing hidden windows costs a lot and has no any benefit - in general. This is a special case and most probably can [only] be solved by a second X server.
From the other hand X is not a monitoring software, so if you wish to monitor anything you need to look for something else. (X is a "simple" drawing app and has no any idea about the apps using it).

In my opinion, if an application needs monitoring, it should provide this very functionality. *My* software uses a logger, and I activate info-level messages by default, although there is usually nothing worth surveying.

However, the commercial software that I helped to either develop, test or document, wrote protocols either as an option or by default. This was one of the very first uses of XML that I remember. As the program in question could be extended with user-provided routines, most of the objects and components were prepared to dump their current state on request.

If none of this is provided, the developers did either not see the need, used different ways to keep a user informed or forgot something.

It would help to know why the OP wants to monitor application-windows and why a screen recorder should be the only feasible way to do it. Some answers are found in the old thread, referenced by ondoho.

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Even for Windows this statement would be exaggerated.

It also does not take into account OP's specific needs.

A screen recorder that only captures a specific window might be difficult to find. Try Movavi Screen Recorder -- it's perfect for this. It is a powerful screen video and audio recording tool for Windows and Mac users. It can be used for screen recording, program usage, and video conferencing. You have the option to record the full screen, part of the screen, or a specific window

reported

OBS Studio for sure.

i have used it with win10 and linux.
its really nice program.