It depends, Aelieanna. If the character was deleted prior to the squish the system doesn’t yet considered it squished, so it goes off of that level range. That doesn’t happen until the character has been logged into.
So for Death Knights any character level 60+ should remain recoverable. Any Death Knigfht under 60 may be purged from the system.
All post squish Death Knights start at level 8 and are consistent with all other characters in that they will continue to remain eligible for restoration at level 50+.