Black Mirror didn’t do that one, but American Horror Stories did:
https://screenrant.com/american-horror-stories-season-3-episode-2-daphne-ending-explained/
Which is surprising because that show normally kinda sucks. Got roped into watching it last year, and I forgot I was watching AHS halfway through and almost thought it was a new Black Mirror.
Sure, unknown, and likely not at all related to this: Russian spy ship escorted away from area with critical cables in Irish Sea and the fact that Russia has said they have a free hand to destroy “enemy” undersea cables.
Perhaps we’ll never know what happened to those cables in the Baltic Sea /s