Migrating default google bucket (multi to single region)

[abrs]

Hello Community,

Due to pricing changes for cloud storage (https://cloud.google.com/storage/pricing-announce) we would like to migrate a part of our buckets to single region. Is this applicable on the default google buckets ?
(example with "artifacts.my-project.appspot.com" for container registry)

1 - Can we migrate default google storage from multi-region to single region ?
2 - If yes, should we keep the exact same name, otherwise how to do ?
3 - How to avoid service downtime ?

Thanks for the help.