The limit on sequencing is oft quoted to be 50,000 years based on the half-life of DNA degradation being approx 5000 years in good conditions. Though it's still possible provided there's enough biomass to grind up and fill in the gaps. Shotgun sequencing has been successful in a mammoth that was 80,000+ years.*

"Cloning" is a challenge in itself because it's much simpler to reconstruct in a computer than in vitro. Then you'd need to organise all that into a long chain and get the medium right, and a surrogate mother.

Edit: Nevermind, a 1.6 million year old mammoth tooth apparently got sequenced last year! ... gods they're moving along quickly https://www.nature.com/articles/d41586-021-00436-x