Ageism is a real factor in tech companies but as the demand grows and tech companies have been around for decades this might go down a bit. May be not for startups but FAANGs definitely will have more aged developers. It’s also important to realize the other factors play in this. Where you are born, your race matters a lot more than many people think. Two people of same age and equal talent but different race aren’t treated the same way in almost any country in the world (Not trying to generalize but it is prevalent)