lhy the Flarum 1.x codebase is written to be compatible with PHP 7.3 and higher. The upcoming Flarum 2.x has bumped this requirement and you will see some more "modern" code. Using new PHP 8 syntaxes usually doesn't bring any benefit to the end user though, only some developers might prefer the new ways code can be written.
Some extension developers have already made their Flarum 1.x extensions PHP 8+ only to get access to these new PHP features, and that's usually not an issue as all forums should be running an actively supported PHP version. The minimum requirements for Flarum core 1.x will likely not be raised, as no more feature upgrades are planned and bumping the system requirements during the security maintenance phase would make no sense.
If you still encounter errors, please follow the troubleshooting guide https://docs.flarum.org/troubleshoot and create a new discussion underSupport with your findings so we can help you resolve it.
