It will also be removed as it is against board policy. Which you are doubtless also aware of.

I have never used markdown manager, but I know that there have been issues with it for quite a while.

I use promotions, which can be run for any period (mine is perpetual, as it's a volume discount) and doesn't seem to have the same problems that MM does.

It just means buyers can't see that an item has been discounted.