Samsung A50's navigation bar hidden when it is inside a case

I apologize if this is a dumb question. I don't actually own an Android phone, just asking for a family member. The navigation bar in a Samsung A50 disappears when the phone is inside a wallet-type case. The only way I found to make it reappear, is by removing the phone from the case. It seems there is a magnet that triggers the navigation bar to be hidden. The owner of the phone told me that this started happening when she updated the OS. I don't have version information at this moment, but will add the info as soon as I get it from the phone owner. Thank you!