This check is not case-sensitive and ignores diacritics (accents).
text_a
starts with
text_b
"Text contains subtext" starts with "contains"
=> false
"Text contains subtext" starts with "tëXT"
=> true
"Text contains subtext" starts with unknowntext
=> true
unknowntext starts with unknowntext
=> true
unknowntext starts with "some text"
=> false