Forgot to turn on Filevault BEFORE migrating a Time Machine backup. Is my data at risk?

[macpokerstars]

I just bought a new MacBook Pro 13-inch 2019.

I migrated my Time Machine backup (an encrypted backup) from old computer (MBP 2015) which had Filevault ON. But I forgot to turn on Filevault.

When I finished the migration, I realised my mistake and turned on Filevault right after.

Does that mean that some residual data is roaming unencrypted on my SSD?
Or that the residual unencrypted data will disappear as I write more data on the drive?

When you encrypt the disk, is the encrypted data written OVER the unencrypted data? (meaning in the same location of the SSD)

Also, for some reason, Filevault turned on instantly. There was no waiting for hours for the encryption to complete, as it has always done on my previous laptops.
Is it normal that it turned on instantly?

 

[Weaselboy]

I would not worry about it. The new T2 equipped Macs like your come out of the box with drive encryption on. All FV does it add a password to that encryption. That is why it enables FV so quickly.

 

[macpokerstars]

Thanks for your response.
I'm wondering what holds the key to the default encryption, if it's not password protected.
If there is no password, what keeps it from being read by unwanted people?

 

[Weaselboy]

Thanks for your response.
I'm wondering what holds the key to the default encryption, if it's not password protected.
If there is no password, what keeps it from being read by unwanted people?

It is tied to that T2 chip in your Mac. So even with no password, if someone took the drive out and tried to read it on another Mac, the drive would see that it is not the same T2 chip code and it would not allow the drive to be read.

Mac computers with the Apple T2 Security Chip - Apple Support

Learn which Mac computers have the Apple T2 Security Chip.

support.apple.com