Raiding Bombardement took more pops than mentioned

[Bl4ckSh33p]

The tooltip says it does not take the last 5 pops but it just took another one and the target planet has only 4 pops left now.
/Edit: down to 2 pops

It's a minor race in steam age.

Xbox 2.0.0 2 with all dlc enabled.

 

[MrFreake_PDX]

I wonder if this is just due to the planet being owned by primitives? I assume this is a save you're playing, if you don't mind checking with a regular empire, that would be great