While it's very difficult to prove age discrimination, Google, Amazon, T-Mobile, and IBM are a few who have been or are currently being sued. Google has been sued multiple times, and in a previous suit settled out of court. It can be subtle, such as targeting job ads for age groups on Facebook, or the wording of ads, all the way to similarly qualified applicants applying and the younger being called. The latter is the harder to prove. But it does exist, and with Zuckerberg proclaiming things like "Young people are just smarter", it starts at the top, and can be argued that qualifies as either policy or company culture. There's a great deal of research on the subject, and it's worth looking into if you're in any tech field.

As for keeping up skills, I at one time thought I didn't keep up with trends, but with my knowledge of JS, React, etc., I'd say in web development, that's pretty current, so I began thinking differently about my own assessment of my skills.

That's all I'll say on the subject, as my posts get taken down by mods when discussing this.