Second 1.21.4 Bêta test

Corrections have been made compared to the first version.

Some users were unable to play the mod because they > encountered an error for which they couldn't find a > solution. This has now been fixed.

Still in beta

1.21.4 is still in beta. I need more time and your tests to determine if any changes are necessary due to the version change. It's possible that some systems are obsolete or simply broken.