I have two iPad Pros
iPad Pro (12.9 inch) (3rd Generation) iPad Pro 13-inch M4
Both with their Apple Magic Keyboard and trackpad.
With iPadOS 17 I could ctrl-space to jump between input languages. Now with 18.1.1 and 18.2 beta this is broken.
On the old iPad, the languages used to show EN, then DE. Now it shows EN DE, EN DE. I went to settings and the keyboards were shown as having English and German input for two physical keyboards. I deleted and recreated, now each keyboard has only one language and ctrl-space now alternates between EN and DE.
On the new iPad Pro, two keyboards are already set with a single input language, but ctrl-space is not changing the input, it types a space instead. There does not seem to be any way to change the input language using the keyboard.
If you feel this behavior is not working correctly or has broken recently like you mention, please file a bug report using the Feedback Assistant tool.
https://developer.apple.com/bug-reporting/
If you reply with your Feedback ID I can make sure it gets to the right team.