Are there any release notes for 2024.0? What are the differences between this and 2023.6?
Well there are change notes on the Phoenix Contact website.
Application note AH EN PLCNEXT ENGINEER - CHANGE NOTES (amazonaws.com)
Are those all the changes?
I am asking because the title of the document is titled „Change notes at a glance“, and not „your comprehensive list of all changes, bugfixes and new features“,
Somehow I doubt that these are all the changes.
I am missing the sentence „Various stability and performance improvements“ 
Somehow I doubt that these are all the changes.</p>I am missing the sentence „Various stability and performance improvements“ ;)</p>
haha, maybe they can go all AppStore-style and simply write that single line.
Well, that list shows that only 2 things were fixed…
Yeah but that seem to be two things from the previous „Kown Issues“ list which I assume is a heavily filtered list at the first place (because I doubt that the Known Issues list is a complete list of all known defects )