By default, the {websafe_tag} variable as well as ALL other functions ASSUME that multiple word Tags will have a + instead of a space to seperate the words in the Tag.
You can change this behavior by adding this parameter to pretty much all functions/loops:
websafe_separator="-"
That example assumes you want to use - instead of +
The reason you cannot just do this for say, the Tag:Tags loop, is because if that Tag, which would now be generated as “multiple-word-tag” in the URL, will not be recognized if it’s clicked and you’re taken to the template with the Tag:Entries loop, because it’s expecting “multiple+word+tag” to be a valid Tag. Adding the websafe_separator="-" parameter to your Tag:Entries loop will now correct it’s thinking