Tires in general have a 10 year service life. Tires are normally stored indoors away from sunlight. 2021 should not be an issue unless you will ride that tire past 2031. You can ask for another tire. Your choice. For me it's good to go.
FYII picked up a set of new Michelin Road 6GT tires for my 2013 R1200RT. I noticed the front tire was in a bag that the distributor sent the tire in when it was delivered to the dealer. The date on the shipment tag is 6-22-2022. The tire manufacture date is "3321" or the first week of August 2021. So the tire has been in the dealer's inventory for 9 months and is almost two years old. Should I ask for a newer tire or is this a non-issue?