I found this oddity. Lincoln looks like he lost 50lbs. almost deathly. Any explanation? Over polished die maybe? Does it have value?
Keto diet. But seriously, although there is a bit of loss near the neck due to some die polishing, the real difference was a design change. Not sure what year the change happened but the cent design has been tweaked many times over it's history. The last tweak in 2010 was the worst IMHO.
Your 1983 cent was struck with a late stage die (worn due to use and cleaning). Plus the new dies used for zinc cents are a low relief design. The 1964 cent is of the old high relief dies which was changed in 1968. Note how design is not so close to the edge of the coin. This 1969 master die was changed again in 1972, and again in 1982. The discoloration of your 1983 cent does make Abe look gaunt. It still has a value of 1¢.