There's a current news story about a thief stealing phones and bank cards from gym lockers and stealing thousands of pounds from the victims' bank accounts:
www.bbc.co.uk/news/uk-england-london-62809151
The thief can take over people's bank accounts if their phone is set to display notifications when the screen is locked.
"Once they have the phone and the card, they register the card on the relevant bank's app on their own phone or computer. Since it is the first time that card will have been used on the new device, a one-off security passcode is demanded."
"That verification passcode is sent by the bank to the stolen phone. The code flashes up on the locked screen of the stolen phone, leaving the thief to tap it into their own device. Once accepted, they have control of the bank account. They can transfer money or buy goods, or change access to the account."
The article advises turning off notifications from appearing on a locked screen and gives instructions on how to do so.
And ideally not keeping your phone and card together.