@Staryhaliny Oh, my goodness. zstd is not very, very new standard! It exists since 2018.
Fortinet has a very bad firewall OS filter.
//EDIT:
OMG! They tell users to fix their bad firewall filter by disabling zstd in chrome://flags
https://community.fortinet.com/t5/FortiGate/Technical-Tip-FortiGate-and-ZSTD-implementation-for-example-Meta/ta-p/301801
Fortigate is like this:
You shall not pass!
//EDIT2:
😎 "Fix" for Vivaldi
Open in address field vivaldi://flags/#enable-zstd-content-encoding
Set dropdown to Disabled
Restart Vivaldi
That will connects to Facebook and other Meta pages.