I don't. We just finished upgrades from 7.4 to 8.0. PHP 8 was release November 26, 2020 - two years ago!
> How do you deal with Nginx/Apache updates given they release more frequently than PHP?
My managed host deals with that.
> You can always host at a managed hosting provider who will take care of this for you.
I have a "managed" host and none of them will make your code compatible. It requires a software engineer and lots of unglamorous work.
This.
The PHP developers are trying to turn PHP into a decent, fairly modern language. This has involved quite a lot of breaking changes in the last few years, and upgrading website code just so it works with the latest version (i.e. no actual improvements) isn't appealing work.