I wouldn’t object to being called “boomer” but I have no doubt age discrimination exists and is fairly widespread. I’ve not been subjected to it, personally, but I’ve observed many instances of people who have.
People, especially men, in their 50’s and 60’s get the worst of it. I’m grateful I never had to seek a job since the late 70’s. However I know others who have, and it ain’t easy. Your best bet is to keep improving your knowledge and skills throughout your career.
I got great advice from my supervisor way back when. He said most people think that doing great work will get you rewarded. He went on to point out there’s a missing factor in that equation: visibility.
You may be doing a great job, and your boss may acknowledge it. However, you will be more successful if you make it a point to let others know. It’s tricky to do without irriating people, but a skill well worth making the effort to develop.
Age discrimination exists because most young people are inexperienced morons. They can get smarter with age and wisdom, or prove they are the exception to the rule.