Many issues with VBE including...
When adding part of a line of code in the editor such as select case<space> and then I pause to think auto syntax checking seems to run (even if its turned off in preferences and irrespective of whether I'm in design mode)
The result is that the line turns red and the space is removed. The consequence is that as I type the next part of the statement the space is removed and I end up with a syntax error.
This issue is irrespective of where I save the document (OneDrive, iCloud or local to the mac) and whether autosave is on or off. Even if I clear all the check boxes in Preferences Editor the problem persists.
Additionally but not obviously related the editor also seems to drop a number of the characters I type. Neither of these issues ever happened when I ran under Windows.
I am running latest 356, latest Big Sur on M1 MBP.