ios 14 mobile safari logs me out of yahoo after a brief time

Ever since upgrading to iOS 14 on my iPhone 11 Pro yesterday, Yahoo Mail via mobile safari logs me out after 5 minutes of inactivity. When I log in, there is no check box to stay logged in. It was fine on iOS 13 and prior. I know that most folks use Apple Mail, but I have a specific use for accessing mail accounts through mobile safari. Any ideas? Thanks in advance.