failed hiding macOS HUD (Big Sur)

[dmndrz]

Hi! The app itself seems to work perfectly on Big Sur. But when I try to hide default macOS HUD in Terminal (after having disabled SIP then reboot) I get this:

mount_apfs: volume could not be mounted: Permission denied
mount: / failed with 66

Then when I try to delete the text in the plist file, it doesn't save the edit. Is it me doing it wrong or are there new restrictions with Big Sur?

[DanielVolz]

Must be a new security restriction of Big Sur. It doesn't work for me either.

[AlexPerathoner]

I can confirm this is a new restriction introduced in Big Sur. There are some workarounds which are (obviously..) more complicated than it was before. Some people fell in a booting loop after trying to make their boot disk writable. I therefore ABSOLUTELY DO NOT RECOMMEND trying this on your main disk. I haven't tried it out yet.

Here's the instructions I found.