In Flutter, the only way to make a blur effect is by using BackdropFilter. That’s why almost all packages that show glass or frosted effects use it, The package you are using is also using the same in it's native code. But on IOS, there’s a known issue. Even if you wrap BackdropFilter with ClipOval or ClipRRect to make it round or curved, you might still see a square or rectangle blur behind it. This happens because Flutter uses something called saveLayer to apply the blur, and on iOS, it doesn’t fully respect the rounded shape when showing the blur. So even if your widget looks round, the blur effect shows up as a square behind it. This bug is tracked here: flutter/flutter#115920.