No one leaves because of "lack of diversity": look at how Bellingham WA exploded in the last few years. Further, the VMware layoffs and Meta/Facebook and Google retrenchment are country-wide and not confined to only Austin.
What is more likely is that Austin, which saw a huge run-up in home prices, is just not as affordable as before. Add in quality of life things like longer commute times, and the end of ZIRP draining available funding...