I've been in this industry for a while. I started out as a system administrator writing a lot of bash and Perl scripts, taking care of mail servers and DNS, and doing a lot of corporate backups. That job is now called "DevOps", and I've made the transition.
I now work in Python 3, Django, Ruby, JavaScript, Kubernetes, and AWS. I haven't been standing still, and I firmly believe the key to avoiding career stagnation is to be constantly learning and educating yourself and never being satisfied with the status quo.
I've been fortunate, as a remote worker, that I haven't really experienced severe negative consequences (at least not yet...knock on wood) from age discrimination. Yet the shadow of ageism is always there, and I hear stories from friends about incredibly insensitive and cringe-worthy age discrimination.
I'm content with my role as a "grey beard" (I'm actually clean-shaven now, but back in the day I had a huge red UNIX hacker beard). But I'm not happy with the way the tech industry treats older workers. I'm supportive of legal protections for older workers in tech. We are not all dinosaurs. Many of us know, for instance, how to sniff out fads from real forward leaps, and we have deep industry experience that can be leveraged by employers open-minded enough to hire us.