Regex is very powerful … for example, if you want only the standard letters and numbers you can use this regex rule: ^[a-zA-Z0-9]*$
This says, take the entire string and check for only letters and numbers. If you use the “regex match” function connected into your branch, you’ll get true for this value “aBc123” and false for “aBc%321” or “!#$%”, for example. So you could condense your entire regex part of your BP to just “regex match” and then modify my example rule to include or exclude the characters that you want.