I am defining a program that has non-required options. When the option starts with "no", it doesn't work as expected. If I change it to "No" it works but is case-insensitive in the code (i.e., I can call the option by no... further down in the code).

This is in Stata 16.1, running on Windows.

Is there some feature of Stata I am missing out on, which is why this is proper behavior?

See below MWE
Code:
cap program drop doesnt_work
cap program drop works
cap program drop works_but_weird

program define doesnt_work
    syntax, [no_option]
    
    if "`no_option'" == "" {
        disp "no option was called ..."
    }
    else {
        disp "no-option used!"
    }
end

program define works
    syntax, [n_option]
    
    if "`n_option'" == "" {
        disp "no option was called ..."
    }
    else {
        disp "no-option used!"
    }
end

program define works_but_weird
    syntax, [No_option]
    
    if "`no_option'" == "" { // note also, case-insensitive (no v.s. No)
        disp "no option was called ..."
    }
    else {
        disp "no-option used!"
    }
end

doesnt_work            // prints "no option was called ..." 
doesnt_work, no_option // prints "no option was called ..."

works                  // prints "no option was called ..."
works, n_option        // prints "no-option used!"

works_but_weird        // prints "no option was called ..."
works_but_weird, no_option // prints "no-option used!"