I didn' know that. That's really interesting, and a bit spooky. I have come across another 22/21 correlation, in the work of John Michell. In his "Sacred Geometry" book, printed after his death, on page 44, is his interpretation of the Biblical story of Hiram of Tyre's molten sea. Sometimes quoted as evidence the ancients used 3 as pi, because of the reference to "ten cubits from one brim to the other, and 30 cubits around".
John lays out the case for the bowl rim being a handsbreadth wide, so there were two diameters, inner and outer, with two different cubits, separated by the ratio of 22/21. This made the inner circumference 3 times the outer diameter. Very clever.
In the case of the Nubian triangular dimensions from the previous drawings, this would give cubits of 1.718 feet and 1.8 feet.