All the life on Mars is now going to be deep underground. It really isn’t possible to contaminate this even if we were to deliberately crop dust the whole plane

All the life on Mars is now going to be deep underground. It really isn’t possible to contaminate this even if we were to deliberately crop dust the whole planet in bacterial spores from Earth. It is not something we need to worry about. I would be much more cautious about some of the moons of Jupiter and Saturn that may have internal oceans. These could be contaminated if we are not cautious, but like Mars they have probably been contaminated by Earth microbes billions of years ago.