In Dutch, we have a quite unique language oddity. It’s the letter combination of “ij”. I won’t go in details about how to pronounce it, because it’s irrelevant to the case. In any case, in our language, this combination is quite common. So far so good, no issues there.
The real oddity here is a situation where we have to capitalise this. If the ij is at the beginning of a word, and that word is in the beginning of the sentence, then both i AND j needs to be capitalised.
Unfortunately, this is not in any way incorporated in the Dutch spelling checker. I don’t even know if it’s possible to add it in there, but it’s rather a hassle if it changes back to “Ij” every time you touch that word. So it would be of quite a convenience to Dutch users.