They say it improves security, but certainly it's possible to have FDE which can be copied onto a new disk --- you're just doing a bit-exact copy of the ciphertext.
https://www.pcmag.com/news/362635/data-recovery-connector-re...
https://9to5mac.com/2018/09/20/apple-t2-data-recovery-transf...
Apple has recently documented a new data recovery process internally for Macs that utilize its T2 chip introduced with the iMac Pro and the 2018 MacBook Pro. The new process for repair staff is being introduced due to the T2 chip’s advanced security features including hardware encryption for SSD storage that isn’t compatible with Apple’s previous data recovery methods used on older machines.
PCMag should update their article.