Thanks for sharing this. I went through a similar experience with COVID and also ended up leaving a long time endeavor.

But I feel like I came out of it completely renewed. I picked up new technology stacks and new environments (GCP, AWS) and I rather than feel like the ability to absorb has decreased, I find the opposite is true: I'm able to learn things even faster now than when I was younger and perhaps more dogmatic.

I also feel that if you can find the right stack, the burden of building systems by oneself nowadays is incredibly low.

Cheers and wish you the best; use mid-career engineers are stuck in a weird limbo-land of expectations and experience.