Yield Concession, disadvantage to putting low yield tax-free bonds in taxable account and equity in TDA?

CFA Level III
#1

I came across reading this: yield concession presents a disadvantage of putting low yield tax free bonds in taxable account and equity in a tax-deferred account?

Can anyone explain this?

Thanks!

#2

You are conceding some yield by using the lower yield tax-free bonds in taxable than if you used higher yielding taxable bonds in the TDA.

#3

Thanks, however this implies we should put lower yield tax free bonds in tax deferred account. Which doesn’t quite make sense to me.