The official blog post announcement is at:
https://blogs.embarcadero.com/rad-studio-12-3-april-patch-available/
The patch addressed a number of issues, including, for the Delphi point of view a slow down of the compiler when executed form the IDE and a changed to the way record constraints work for generics, which has been reverted to the pre-12.3 behavior.
I highly recommend installing this patch.
If you install it via GetIt, you get the proper indication of the installation in the about box, but rememebr you also need to manually install the udpated PAServer.
