At least for me, on Android 17 with a Google Pixel 9 Pro XL, the Firefox logo in the app's themed icon is too big in the icon's circle, making it get too close to the edges. It's a very small detail, yes, but the logo is noticeably larger in the themed icon than in the normal app icon, and having such little padding between the edges of the logo and the edges of the app icon makes it stick out noticeably against all the other themed icons, which goes against the point of having themed icons in the first place.
These images illustrate the issue.
