The travails described in this post could just as well be my own, except that my career disintegration began in 2017 or so, soon after I turned 50. I've pursued every job search strategy this author lists, and encountered the same lack of progress. I've just submitted an application to work at the local grocery store for $17/hour.
We can blame ageism, offshoring, AI, what have you. The basic problem is that the technology industry has never prioritized hiring or retaining experienced people as developers. Our roles are persistently misunderstood by management, and "AI could do that!" is just the latest misapprehension.
Meanwhile, be kind to your DoorDashers and store clerks.