I was getting the chic tinted outfit achievement, filling a cauldron with blue ink and painting the full leather armor blue. I was about to put away my painted armor that I wasn't wearing until I received a notification with the achievement of you need a mint gum, although he had already given me the Chic Tinted Outfit achievement before that he gave me the You Need Mint Gum achievement. I must say that I get notifications a little late but still never I've been to the end.
Conclusion I received both achievements but I didn't get the "you need a mint gum" achievement at that time.
I'm having this same issue on Nintendo Switch.
I got the "Mint Gum Required" achievement even though no one ever reached The End in the first place.
The conditions under which this occurs are unknown.
It happened to me while I was riding horse after harvesting cocoa beans in the jungle.