One possible reason for the lack of interest in older coders is that they're largely white and male. Hardly a sympathetic demographic in the current cultural environment.

For myself (note: am old), I'm just following the advice I've always given to other minorities that are discriminated against to various degrees. Which is: don't whine, and play the cards you were dealt as best you can.

The FAANGS may not, but many other employers can spot talent when they see it. Keep looking--there's a niche for everyone.