If you are using a piaware 4.0 or older sdcard install, and you had previously upgraded raspberrypi-sys-mods yourself (which installed the microsoft repository), and you have not modified that configuration, then upgrading to 5.0 will comment out the microsoft repository config.
If you are using a piaware 4.0 or older sdcard install, and you had not previously upgraded raspberrypi-sys-mods yourself, then upgrading to 5.0 will install a placeholder file to prevent a future upgrade of raspberrypi-sys-mods from installing the microsoft repository config.
If you are using a fresh install of the 5.0 sdcard image, the microsoft repository config is not included (and the installed version of raspberrrypi-sys-mods is past the version which would try to do the install)
If you’re not using the piaware sdcard image, then repository management is up to you, piaware doesn’t touch it.