You could fix Qing not being able to take the decision "Construct the Forbidden Palace" (Manchu can take it but Qing can't). It dates back to something like 1.04 and is a fix that would take 0.45 seconds and no testing.
I'd say it's major enough.
Seriously, though; I keep reporting it after every patch but to no avail.
Noted, will fix for 1.14.
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