Have you guys tried a factory reset yet? That's really strange.
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Samsung's gallery icon is a flower. If you have any app folders in the drawer it might be in there. Otherwise, you may need to reset the phone.
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@userL9bKGmxedj are you in the US? Have you activated Secure Folder by chance? (If not, could you try activating that really quick?) Pull down twice to access quick settings and find Secure Folder.
It's really weird you're not seeing a gallery app to be honest.