I took to The Google to get more information, assuming that an interesting phenomenon like this would be well-documented and discussed (and there would be an explanation for why it occurred every two years approximately on the solstice, instead of annually).
First red flag was that almost all the search results were for Tumblr/Pinterest reposts of the original.
Second was this discussion on Quite Interesting, in which a user points out that:
There is indeed a place in Ireland, named bru na bainne (the abode of the Milky Way, modern name Newgrange), although it looks nothing like the picture shown above, and the alignment is with a certain star group, (modern name Orion), the Lord of the Northern Winter, and not with our galaxy’s edge.
The place in the picture would have to be close to the Equator for the galaxy to appear vertical on the dates given, just before the summer solstice. Orion is Lord of the Summer, south of the equator.
This led me deeper into the rabbit hole; Brú na Bóinne (correct spelling) does indeed exist and it does have a very different appearance than that shown in the photograph, along with a winter solstice alignment.
I pinged an astronomer friend to factcheck the rest of this, but he wasn’t around, sadly.
That said, I feel pretty comfortable calling utter bullshit on this.