Consider using the native Network Activity Indicator

I think the centered activity indicator is a bit distracting, and should be replaced by the iOS indicator in the status bar (https://developer.apple.com/design/human-interface-guidelines/ios/controls/progress-indicators/#network-activity-indicators).

For edge-to-edge devices (iPhone X, Xs, Xr, maybe the new iPad Pro), this indicator does not show though, so either, these could keep the current indicator, or something like this: https://www.futuretap.com/blog/fix-for-the-missing-network-activity-indicator-on-iphone-x