The Deeper mining special project can be used to store an arbitrary number of extra androids, completely bypassing the storage capacity of the colony's android housing. This enables one to get effectively infinite workers given enough time and android production, which I do not think is an intended behavior.
This could be fixed by changing things such that androids assigned to specific projects, including Deeper mining, keep their spots reserved within the colony's android housing so newly built androids don't take their place and the total android count doesn't overflow.
Additionally, the number of workers provided by androids should be limited not just by current android count but also capacity. E.g. if your colony has 1500 out of 1250 androids, the 1250 (minus specific assignments) is added to the worker pool instead of 1500.