For what it's worth, my staging forum copy works fine.
Xenforo 2.2.15 (latest official update at the time of writing), and PHP 8.3 (also latest at the time of writing).
As a man falling from a skyscraper says: "so far so good."
Tested it with PHP 8.2 as well - all looked good.
Will try to update the "production" forum in a day or two and see how it fares.
In case it's relevant:
I ran the update with PHP 8.0 (what the forum was running on until then).
Only after the update looked to have went well did I start testing the newer PHP versions.