Czech keyboard - Ł
This is a mystery for me... why Czech keyboard has Polish letter? There is also serbo-croatian Đ... why?
I realized that Polish is not the only language that uses Ł - Sorbian languages use it, too. Now it makes more sense because Sorbian languages share a lot of diacritics with Czech. German letters make sense too because Sorbs live in Germany (some of them also in the Czech Republic).
Certain dialects in Silesia and Moravia use the Ł /w/ sound and the letter is used to write it. It was used in "standard" Middle Czech (say until the 17th century) but Jan Hus already complains at the beginning of the 15th century that people don't distinguish it from L in speech properly (it was a hard L, not /w/ back then, even in Polish).
That said I have no idea why is it on the keyboard you use (mine as well, even in Linux). There are multiple variants of Czech PC keyboards. It is not on a normal typewriter machine IIRC. Or it was well hidden. What we did have even on typewriters is the umlaut for ü,ä,ö because of so many connections to German.