It seems to be related to this issue. Like that poster, the page generally loads slower for me during the 1-2 minute period. Once it finally does load, it is without CSS.

Google’s Search Relations team explains how CSS affects SEO, addressing myths about class names, pseudo elements, and page ...

Google's John Mueller and Martin Splitt spoke for just under 40 minutes on the topic of CSS and SEO. They covered why CSS ...

They’re generally CSS and JavaScript files that determine how a page looks or functions. Current web pages process dependencies inefficiently.