Had a similar experience trying to change my billing country for Google One. The support staff would not reassure me that I wouldn't lose any data by cancelling

Had a similar experience trying to change my billing country for Google One. The support staff would not reassure me that I wouldn't lose any data by cancelling my plan, waiting until it expires in a year, and resubscribing with the new payment method. I asked multiple times and they just kept dodging the question - turns out you also do have a 30 day grace period in which you can resubscribe, so it worked out fine.