So heres what I’m guessing happens
(Or rather Bradykin who found the bug and is unable to log into the forums does)
Delhi Keep Research is snapshotting the # of scholars in mosques at the time it is queued up.
When that number changes, either adding or removing scholars, the UI value changes correctly but the underlying speed value does not.
The same effect occurs if the keep is added to or knocked out of the mosque influence region while the tech is ongoing - I forgot to add this to the video, but it will keep the speed of tech that it had snapshotted while correctly adjusting the UI. The end result of these cases is identical to the ones displayed in the video.
This was not reproducible with other techs - I tested greased axles from the siege workshop, armoured hulls from the dock, and military academy from the blacksmith, all worked as expected. It happened with garrisoning both in mosques and madrasa, this video uses a madrasa for convenience.
Heres a recording of the issue for someone to reproduce.