Are we still required to return cancelled license plates to the state?

Leased a new car and got new plates.  I already cancelled the reg on the car I sold to the MA dealer, but didn’t see any instructions on the CT DMV website about whether I need to return the old plates.

Go online. Select cancel and keep plates

Its hilarious that a page that is supposed to instruct you on returning plates says nothing about plates.

Returning Connecticut License Plates and Cancelling a Registration

Perhaps the online form indicated on that link says something about returning plates.

Make sure to contact your local assessors office. That is something many forget. Know several who moved from CT and didn't notify their former assessors office and then got taxed on cars they no longer had. Fun times they had trying to get that car removed from their former town's tax rolls.

A google search turns up this PDF from Guilford. Don't know how old it is or if it still applies. It indicates the plate gets returned.
http://ci.guilford.ct.us/wp-content/uploads/Returning-plates.pdf

Because I couldn’t find current instructions about actually returning them in person at a DMV office or via mail, I’m thinking they stopped taking them back because of Covid.

Absolutely no need to return plates, (did registrations at a car dealer part time up to this year).  Good idea to check with your town a short time after cancelling online, shockingly the DMV isn't foolproof.  Turned mine into cheese graters at the range

When  you cancel your plates at ct DMV online, you can simply opt to dispose of your plates, then just throw them in the trash.

You don’t need to dispose of them, and they can be reused the next time you register a vehicle; this will avoid a fee for the cost of the physical plate.

I would advise not driving around with them in another car