I'm also having the same issue where attempting to start RStudio with R 4.1.0 for arm64 on my M1 Mac gives the error:
The R session process exited with code **6** .
### ERRORS
`dyld: could not load inserted library '/Library/Frameworks/R.framework/Resources/lib/libR.dylib' because no suitable image found. Did find:
/Library/Frameworks/R.framework/Resources/lib/libR.dylib: mach-o, but wrong architecture
/Library/Frameworks/R.framework/Resources/lib/libR.dylib: stat() failed with errno=1`
Running the terminal commands outputs arm64
for both of them. Hope that helps!