Domain fronting is critical to the open web https://blog.torproject.org/domain-fronting-critical-open-web

Tor is an open network, and all Tor relay IPs are public, which makes it simple for repressive governments to block them all.

Meek is a domain fronting pluggable transport that censored users rely on to bypass these blocks. Since Amazon and Google have blocked domain fronting, only Microsoft's Azure cloud still works, but Tor hears Microsoft might block it next.