> My understanding was that the name would be pronounced the same way
No, part of the rationale for the change is to reflect the different pronunciation (Türkiye) has three syllables
> but as a native English speaker I don’t even know what the umlaut does to the sound of the u.
While there is a change to the first vowel sound, and I think an even more subtle change to the second, the biggest difference is the existence of the third syllable, which is pretty evident from the spelling, even to most native English speakers.
No, part of the rationale for the change is to reflect the different pronunciation (Türkiye) has three syllables
> but as a native English speaker I don’t even know what the umlaut does to the sound of the u.
While there is a change to the first vowel sound, and I think an even more subtle change to the second, the biggest difference is the existence of the third syllable, which is pretty evident from the spelling, even to most native English speakers.