How to delete a white grid app

First, make sure that deleting apps is not disabled: Go to Settings/Screen Time/Content & Privacy Restrictions/iTunes & App Store Purchases - Change Deleting Apps to Allow.

Then hold your finger on the icon, chose Edit Home Screen from the pop-up menu, and tap the “-“ on the icon.

Usually a forced restart will clear it

https://support.apple.com/guide/iphone/force-restart-iphone-iph8903c3ee6/ios

Make sure Screen Time is turned right off first.

Nuke it

Backup and restore

(1)How to back up your iPhone, iPad, and iPod touch – Apple Support

(2) Restore your iPhone, iPad, or iPod to factory settings – Apple Support

(3) Restore your iPhone, iPad, or iPod touch from a backup