This compulsive need for data is such a mental crutch. Reason from first principles. Use logic. You don’t need to be spoon-fed data from a scientifically rigorous study in order to deduce basic cause-and-effect relationships.
There are sub-$60K H1B jobs. That's below my $55K starting salary as a fresh grad which, after adjustment, is $100K today. That was in an era when CS grads were pulling $100K with no experience so by no means extravagant for the time.
We've had decades of STEM hype but somehow can't produce college grads to do entry level tech work?
As a small amount of data, my asking salary has never been less than the highest paid H1B at a company plus another $30k/yr, and I've always been offered more than I've asked, despite the H1B position being more senior. That doesn't prove wages being dragged down by itself, but it's evidence of H1B workers being paid less than the legally mandated "actual wage", and ECON 101 can take care of the rest in terms of the expected effects on the market.
US Tech has the highest salaries world.