For reference to the Atlassians who may be collecting feedback on this thread, what @KsaweryBuczkowski is referring to is the fact that the out-of-the-box AMPS does not work to build (for example) Confluence 8.8+ apps, or anything else depending on the new platform. This is because vendors are now required to bundle artifacts that were previously system-provided, but the default AMPS configuration actively prevents developers from bundling these (meaning the build fails), unless certain exceptions are added to the POM.
In short, the provided tooling doesn’t even work unless one dives into various CDAC threads to figure out how to fix it.