In my installation of release R2020a line 23 of the normalize.m included in MATLAB is a comment that's about a third of the way through the help text. This suggests to me that you've created or downloaded a normalize.m that's taking precedence over the one included in MATLAB. To check, what does this command show?
which -all normalize
If you see any normalize.m files listed that are not under your MATLAB root directory (which you can see by running the matlabroot command) try renaming them.
You might also want to check that the directory in which that other normalize.m is located doesn't have other functions that are taking precedence over other MathWorks functions to avoid this same type of problem with those other MathWorks functions.
