The specified secondary replica is not currently synchronized, therefore performing failover of this availability group might ...

The specified secondary replica is not currently synchronized, therefore performing failover of this availability group might result in the loss of any transaction that did not reach the secondary replica prior to the availability group failing over.

To confirm the failover of the availability group '$$TypeName:AvailabilityGroup@urn$$' to the specified secondary replica '$$ssms:Name@context$$', click OK.

Following successful completion of the failover operation, the new primary databases will be online, but all the secondary databases will be suspended. You will need to manually resume data movement on each of them.