This issue is specific to Dutch. Capitalisation should convert 'ij' at the start of a word to 'IJ', for example 'ijsland' should become 'IJsland'. Tests & results: i18n test suite, Tailoring, Dutch. https://w3c.github.io/i18n-tests/results/text-transform#dutch_tailoring When the text is labelled as Dutch, Gecko passes, but Blink and Webkit fail. Priority: This is a basic issue for Dutch.
(W3C is tracking this issue at https://www.w3.org/TR/2022/DNOTE-latn-nl-gap-20220126/#transforms)
<rdar://problem/88380655>