> I've been in software professionally for over 20 years and in that time I have only left 1 employer before 5+ years

You've had a somewhat traditional career there by HN standards. Most of Silicon Valley was promo-hopping ever 1-2 years for the whole middle period of your career (somewhat curtailed now by the job market). It was really popular to FAANG -> startup for 6 months -> FAANG-1-level-up for a good chunk of the 2010s