Debated. A link to the wine god is not sure.
The mask was in Crno Jezero Cave, on the Pelješac peninsula, in Croatia. The page calls it 2,000 years old, and also dates it to the 4th or 3rd century BC. It is terracotta and hollow, with a small hole at the top, so it may have hung up. The cave was an Illyrian sanctuary from the late 4th century to the middle of the 1st century BC. Small Greek pots and wine cups were left there.
The page leaves open whether the mask and wine cups belong to Dionysus, or to a local god like him.
https://www.ancient-origins.net/news-history-archaeology/greek-theater-mask-00102806