That's what bothers me.
Because 20 years ago they all agreed that it was a different age.
Are you smarter than you were 20 years ago?
They're always working with the data they have. When new data arrives, from new telescopes and better technology, what do you suggest they do? Supress the new information? They don't do that. They welcome the opportunity to revise their understanding, in the light of the best available information. Why do you find this objectionable?
Actually, that's not quite true.
20 years ago, give or take a few years, the consensus was that the Universe was somewhere between 10 and 20 billion years old. There was a fair amount of "slop" in their estimates at that point in time. Today, they have more refined techniques available, and much more data. So they now think it's about 13.5 (+/- 0.5) billion years old, which is well withing the estimates of 20 years ago.