Holy crap, Microsoft....
A) Shouldn't this interaction of the restoration script and custom keys have been caught in testing at some point? If you are going to support KeyVault keys, shouldn't you have tested to see what happens to those customers in a failover/DR event?
B) So you restore the database, missing 5 minutes of data, and you rename the database file? There goes any automation your affected clients might have in place. And of course that might be 5 minutes of important DB transactions that are missing.
C) And it seems you took your sweet time letting customers know that this was going on. Meanwhile, they are freaking out because their databases are disappearing/reappearing and their own automation and various systems monitoring is breaking down.