[quote=@Lucius Cypher]
Pretty sure I’m 5e diagonals are just 5 feet. Or at least that’s how I’ve been told they work, as I remember how pleasant a surprise it was when I came from the Pathfinder system into 5e and learned diagonals no long take 10 feet of movement after the first diagonal.
[/quote]

They are by PHB rules. DMG suggests a spatial variant to count every second one as ten, however. And I cannot remember if we established any rule about this before.