You are spot on. I've had Decades of experience and success in this industry. However this year I was laid off in one of those 6 to 10% staff lay off things. Since then I've applied to over 100 jobs I've had at least eight interview processes.
I go through two to four interviews some of them two to three hours long. And I get to the very end, and then I never hear from them again.
Some have me go through leet code type algorithm questions online with 20 minutes to solve the problem. For me, that's pretty much impossible. Others have me spend several days creating a project from scratch, they review it and maybe they talk to me about it afterwards.
Others don't do a very good job of hiding the ageism, e.g. insisting I tell them what year I got my CS degree.
Given the level of experience I have with new technologies as well as old, I find it hard to believe that I'm not fit to be employed all of a sudden.
First piece of advice, do not be over the age of 50. It won't matter how good you are.
Second, even if you think you're really good at interviewing and going through the application process take seminars and classes on the topic and keep tweaking.
Third, it doesn't matter if you completed successfully one or more multimonth projects in a particular technology. If you don't know every little detail when they interview you, you are immediately written off.
I had one not even bother to interview me because I did not have enough years writing React code.
Another wrote me off because it has been a few years since I tech lead an Angular project. My most recent company used React. The one before used Angular.
Apparently we must spend all our personal time continuing development on technologies not in use for our jobs at the expense of our families or we aren't worth the trouble.
Oh yeah, and we must be able to succeed solving random algorithm problems in under 20 minutes on the spot. That means we basically need to be able to solve them all because we'll never know which one will get.