The closest thing I could imagine would be 'woodland goosefoot', Chenopodium standleyanum. We have a lot of natural ecotypes of C. album (lambsquarters) that come on in the spring, but the one in our
yard that looks like what you have comes on in July and August. It's rather spindly and has more narrow leaves at maturity than most others more closely related to C. album.
If this link is good, it has a photo of what we tend to see at our place in northern Minnesota (USA):
https://www.inaturalist.org/observations/4017850
Best guess anyway.....