getPagesTSconfigPreInclude signal must not alter pre cached PageTS
https://review.typo3.org/#/c/30921/ introduced the getPagesTSconfigPreInclude signal, which made altering the PageTS possible before it's cached.
Despite many arguments against introducing that signal there, it has been merged anyway. As a result, getPagesTSconfig is not indempotent any more and can create compromised PageTS cache entries.
Also the use of signals in that part of the core feels plain wrong as we rely on a mechanism brought by Extbase rather than using regular hooks like throughout the rest of the core.
Instead of modifying the PageTS before it get's cached, I'd place the signal after the caching, making the cache entries indempotent.
We need to have a look at who is using that signal in what way and if modifying it must be considered breaking.