Need Help Identifying This Ancient Nummus, Follis, Ae4?

It's a Late Roman bronze. The reverse type is "votive"; it's a bit blurry but the central inscription says "VOT X MVLT XX". Several emperors issued coins with that type - essentially, any of the mid-to-late emperors who managed to reign for 10 years issued this design. The reverse legend very roughly translates to "vows made on year 10, many more for year 20".

Options are: Julian II, Valens, Valentinian I, Valentinian II, Theodosius I and Arcadius. Of these names, "DN THEODOSIVS PF AVG" is the best-fit for the surviving obverse lettering, so that would make your coin Theodosius I. The mintmark might be SMK, but that's even harder to be sure of. Numista similar example: https://en.numista.com/318528

It's certainly "overcleaned", but it might have been heavily corroded to start with. I'd assume it to be genuine.