In many languages, Thai and Vietnamese being examples, multiple marks may be added above letters. Normally extra line-spacing is incorporated to allow for this. The main heading in the title bar has line-spacing of 1.1em, which is not enough, so such marks get clipped. I’ve even seen plain ol’ apostrophes get clipped.
This will vary depending on font, so may not show up for everyone. But it’s good practice to leave plenty of headroom, especially in the title.