So I just found this sideway generatered ruined portal. I looked it up and it doesn't seem to be intentional.
Seed: -5795350245757626877
Coords: /tp @s 48 53 -656
Linked issues
is duplicated by 7
MC-214230
Ruined portals are sometimes spawned horizontally instead of vertically
Resolved
MC-216058
Horizontal Nether Portal ?
Resolved
MC-227668
Broken Portals
Resolved
MC-228068
One Type of Ruined Portal Generates
Resolved
MC-239458
Chance of Portal Ruins incorrect axis offset
Resolved
2 more links
it's a variant of this structure