Mail still taking up 3GB when it’s deleted?

painfully short of storage space on iPhone 12 64GB so am deleting everything I can including mail. Still shows as mail taking up 3GB. Have tried offloading, deleting the app and restarting the phone. 3GB still there.

its Gmail that’s taking up the space … do I need to do something in google?

This apple storage stuff is driving me nuts! Don’t get me started on photos and iCloud … are they trying to make us all upgrade our phones?!!