While I share concern about api changes, to be fair we must recognize that Lazarus 2.2.0 is the (stable) release version. Main/Trunk/Fixes is development.
The real issue will crop up when the next Lazarus release is in sight, will it contain this new content ? History indicates it will. There is two parts to the new content, the code in LCL that does something new (?) and, separately, the new content that ends up in libQt5Pas. Our problem is they both arrive at the same time and most distributions have some lag time, some have quite a lot of lag time.
Concentrating on getting the libQt5Pas changes visible BEFORE the lcl changes might be more productive.
Or, as I mentioned previously, having a formal release of libQt5Pas as a standalone product, well ahead of Lazarus might help.
Davo