BAMP doesn't work on Safari 13.0.4

[kevadsett]

I get a blank page when navigating to the bamp instance, and three of the resources are failing to load with the following error:
kCFErrorDomainCFNetwork error 303

This is happening for styles.[hash].css, scripts.[hash].js main.[hash].js

[chiguire]

I can't reproduce this on latest Safari 13.1.2