Oh, wait, this is because CRAN does not have binary packages available for these packages. E.g.: CRAN - Package classInt shows
Version: 0.4-10
[...]
macOS binaries: r-release (arm64): classInt_0.4-9.tgz, r-oldrel (arm64): classInt_0.4-9.tgz, r-release (x86_64): classInt_0.4-9.tgz, r-oldrel (x86_64): classInt_0.4-10.tgz
So RStudio is right, there is a newer packages available, just not in the macOS binary form, which is the default package type used by install.packages(). If you really want to update them, add type = "source" to the install.packages() call, but note that you might run into installation errors if you are installing packages from source.