"high level a certainty" --> "high level of certainty"

[saravananmk]

https://http3-explained.haxx.se/en/h3-push.html

Original:

Problematic
[...]

Pushing is never "free", since while it saves a half round-trip it still uses
bandwidth. It is often hard or impossible for the server-side to actually know
with a high level a certainty if a resource should be pushed or not.

"high level a certainty" --> "high level of certainty".