I will also add I have been offered a copies of a common troop that I already have ascended to max level 20. According to the offer this is to “help complete tasks in Khetar”. Buying the additional troops would not make a blind bit of difference to any of the outstanding tasks:
Upgrade x troops to level 20 - this troop was already 20 so makes no difference
Upgrade pets to level 20 - a troop was offered not a pet so wouldn’t help with this
Upgrade x troops to shiny level - this troop is already level 20. adding more is not going to make it shiny.
I dont recall ever having an offer to buy more copies of a troop that is already at level 20. Therefore this is almost certainly a new emerging bug.