Property Line 3’ onto Neighbor’s Lot

We just had our property surveyed, for the unrelated reason of trying to determine if a tree, which requires maintenance, is on our property or City property. The surveyors left stakes defining the corners of our lot at both the front and back of our property. We were surprised to find that our true property line is about 3’ into our Neighbor’s lot.

I am wondering if I have any recourse here or if this fall under a Possessory Claim in their favour? We have lived here for 12 years and really aren’t the shit disturber type, but I am curious if this has any monetary value?