Interesting!
Salesforce will no longer enforce the disabling of Ref ID in Winter'25 release. Now they just recommend the migration as a more secure threading than Ref ID.
Now you should still migrate from RefID ASAP - you might have issues with those ids being different between Production and lower environments.
Example: I had one client that used a formula like below to match the Ref ID and suddenly Salesforce started generating a different Ref ID only on the UAT environment. Their formula was no longer matching, resulting in duplicate cases (luckily only in UAT).
LEFT($Organization.Id,5) & "0" & SUBSTITUTE(RIGHT($Organization.Id,10), "0", "" )& ".!" & LEFT(Id,5) & "0" & SUBSTITUTE(Left(RIGHT(Id,10), 5), "0", "") & RIGHT(Id,5)
