You shouldn't worry about falling out of the technology rat race. Everyone's stack is different, you would be lucky to time learning a technology with a particular job opportunity that is using it. You may as well just research it the weekend before the interview and be upfront about your ability to learn it.

You can't know every technology and in 5 years you will probably be applying for jobs with tech that doesn't even exist yet.

I'm not at all talking about knowing the latest tech when I say your skills may suffer. I'm just saying that in my experience, sometimes in a chill job your fundamentals as a developer can suffer. You can literally get worse at programming if you aren't challenged.

However, if you are an internally motivated and driven person, you can take that extra time and energy you get from the chill job and learn all kinds of things and become a much better engineer. The situation is whatever you make of it.

Well I think my skills suffer more because of work: after a day of "being productive" at work, I no longer have the time and energy to explore and learn new stuff, which is how I gained and expanded my skills in the first place.

Yes, the extra time you get from the chill job can go either way. It's whatever you make of it. If you use the time to learn, you can definitely learn more at a chill job than at a hard job.

In certain parts of governments, non-profits and academia, can be found jobs which both (a) have lower stress / better work life balance, and (b) use innovative tech which keeps one's skills sharp and up to date. These jobs don't typically pay amazingly, but sometimes have a good pension plan, and the option is always there to go back to well-paid higher stress workplace later to fix finances if required....