TYPO3 v8 has reached its end-of-life March 31st, 2020 and is not maintained by the community anymore. Looking for a stable version? Use the version switch on the top left.
You can order Extended Long Term Support (ELTS) here: TYPO3 ELTS.
The Page TSconfig primarily concerns configuration of the modules in the TYPO3 backend. It may also relate to values in the frontend display occasionally.
The Page TSconfig for a page is accumulated from the root and extends to cover the whole branch of subpages as well (unless values are overridden further out).