I'm a 42-YO Dev and a very late bloomer (start of career and learning).
I'm definitely having an existential crisis, more so because I work at a startup. I'm quite certain I'm the oldest in the place, and I feel I stand out for the wrong reasons now.
I've seen a lot of the same things repeating themselves, I find the work repetitive, and my memory is not what it used to be. The problems I'm solving are not "cool" anymore nor new.
I also find I am less flexible - this is difficult when trying to reason with younger ppl in higher positions.
I've built up years of knowledge and made many mistakes that I have learnt from, so naturally I want my next step/role to be closely related to software development as possible. I am not a good leader or manager, so my only option really is to move up into the design/arch or BA work, but both are hard to get into if you don't have experience.
I had kids late, so the last half decade has flown and I've somewhat neglected my career.
It's a weird situation to be in.