Every single source file has been heavily modified and moved in this release. Initial (source code only) support for SDL2 has been merged in. We also support compiling with SDL1 in the same code base, so the migration to pygame 2 is easier. pygame 2 will be released with SDL2 being the default backend when some remaining issues are ironed out. The 1.9.x releases will continue with SDL1 until then. Also, the C API of pygame is undergoing a transformation with lots of cleanups. Then there have been plenty of other cleanups all throughout the python code as well. There's still lots to clean up, but things should be significantly easier for people to contribute (? hello and thanks new contributors!). The documentation has been improved with better examples links, search functionality, and improved navigation. Support for older Macs, and newer Macs has been improved. The mask, midi, draw, and math modules have gotten lots of polish with rough edges removed.
https://www.pygame.org/news/2019/3/1-9-5-released-into-the-wilds