I do not know if it will help in your case, but I just managed to make it work on my Intel MacOS15 CTL 16 machine with the following recipe (thanks to @StephanH and web):
# remove the current Command Line Tools
sudo rm -r /Library/Developer/CommandLineTools
# Reset xcode-select
sudo xcode-select -r
# Then install. You will be asked to click a button
sudo xcode-select --install
# Go in the System Settings -> General -> Software Update
# if there is a new version of the Command Line Tools, update it.
# Install ROOT
git clone https://github.com/root-project/root.git
mkdir root-build
cd root-build
cmake ../root
make -j8
compared to what I tried before xcode-select -r
seems to be the magic.