I just wish hiring managers saw it the same way. It's hard to explain how your last major project was a web enhancement that would have taken a couple days on a virgin codebase, because for you it involved a month of excavating through multiple strata of code dating nearly two decades old, spread across three codebases, two backend languages, a code generator which no one working there understands anymore, and a library who's documentation now only exists on the wayback machine.
A secret I’ve learned is you only need one job, so you don’t need to take just any job or be hireable at every job. It might take longer, but finding a manager that “gets it” is very important. The most important thing is to find someone who recognizes further that a team is more than the sum of its parts, that each individual is unique and not a cog to be evaluated on a metric rubric and forced into compliance with some idealized engineer. They do exist - I was one for many many years. I’ve recently given up in disgust though and switched back to IC, but senior enough I can shape how managers manage engineers. Regardless, my advice is, if it’s helpful, find the right job with the right team and the right company. It’ll take longer, may pay less at first, but finding the right place that respects work at its value not at its marketability is key to any successful career.
Or a library who's code now only exists on the wayback machine... and of the modified version that you actually use only a single copy exists on an old machine that one of the devs in the company never bothered to hand in for recycling...
Never mind that it's part of a decade old contract stipulating a quarter century support...