I chose to sort my collection items in alphabetical order. Webflow support pointed out that alphabetic sorting will be in this order:
Numerically (keep in mind that even if your number is 10, it will sort by the "1" first)
Uppercase letters alphabetically
Lowercase letters alphabetically
Characters with diacritics (a diacritic is a sign, such as an accent or cedilla, that is written above or below a letter to indicate different pronunciation)
In my opinion it does not make sense to list a collection item starting with "B" before another starting with "a" just because one is written with a small vs. a capital letter.
In German language, we also have special characters such as ö, ü, ä, etc. They should be listed in the alphabet like A, a, Ä, ä, B, b, ... instead of listing all collection items starting with a special letter at the end of the list.
I wish this to be changed because it does not look professional.