I had the same issue and fixed after 4 hours
global.scss file
body {
margin-top: constant(safe-area-inset-top);
margin-top: env(safe-area-inset-top);
}
ion-tab-bar {
margin-bottom: calc(4px + env(safe-area-inset-top));
}
i did used safe-area-inset-top for margin-bottom to fixed this issue.
if you have this issue in top header like below image
in varriable.scss in .ios add below code
.ios{
--ion-safe-area-top : 0 !important;
}