(Port) Wine of the month January 2023: 1897?

Is this Madeira, Sherry or Port? Although some very experienced people were tasting and discussing, no one could say for certain which of the “usual suspects” we were drinkin. Tasting-wise it was all Port. So salty notes (Madeira) or other rather Sherry-typical flavors could be detected, but there was one very unusual taste in the wine, that neither of us had experienced yet. Bottle, cork and color showed us, that this was an authentic 1897.
Medium intense, brown reflexes in the reddish color. Malty notes, coffee and this rather peculiar taste in the nose. Same on the palate with some extremely nicely integrated acidity and good supporting tannins. Long aftertaste. 18/20

My Swiss friend lifted the mysterious curtain: Due to a shortage of brandy in this rather great Port year, the producers fortified with scotch, which led to this taste, that no one had before...