How to enable HTTP/3 in Safari 14 on macOS Catalina?

It's said that the safari 14 will have HTTP/3 shipped, but I have captured packets using Wireshark find that no QUIC packets were captured. How can I enable HTTP/3 on my Mac? Is it because HTTP/3 will only come alone with Big Sur?

It seems that QUIC is implemented in user space. Why apple wants to integrate HTTP/3 into the OS level.
Settings > Safari > Advanced > Experimental Features > HTTP/3

From Monterey v 12.2 (21D49) I'm running Safari Technology Preview Release 140 (Safari 15.4, WebKit 17614.1.1.4) and I installed and verified I can get HTTP/3 connections to work through CURL via the quiche client there. For testing, I also disabled all router firewalls and restarted the browser. I'm still not able to see h3 connections in the web inspector tool with the HTTP/3 flag enabled under the Develop > Experimental Features menu. Has anyone been able to see http/3 traffic in any of the safari builds? I'm not sure why I never do.

I am also seeing this - Monterey 12.5.1 but only on my MacBook Pro with and M1 Pro

The same here. MacBook Pro 15 inch 2021 (M1 Pro) Monterey 12.6, Safari 16.0. Http/3 enabled in experimental features, all steps are done, tried everything. Cannot see http/3 traffic.

At the same time http/3 works fine on iOS 16, iPadOS 15 (with appropriate setting enabled)

How to enable HTTP/3 in Safari 14 on macOS Catalina?
 
 
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