It is certain that it belongs to Rumex of Polygonaceae. The seedlings of this genus, such as Rumex crispus, Rumex dentata, Rumex pubescens, Rhubarb, etc., are very similar, and you can't be sure which one it is just by looking at a picture. But it is definitely one of them. You can search for related pictures on the internet and compare them, and see which one is combined with the shooting environment.

I think it's probably Rumex Batian Rumex.

Supplement: If there are any picture books about weeds, you can compare them with the pictures of Rumex crispus, Rumex denticulatus, Rumex Buddleja and Rhubarb of Rumex of Polygonaceae. I wish you an answer.