This article published by Daily Mail claims oat milk is linked to a cancer-causing chemical. While a harmful chemical called glyphosate has been found, as tested in an Environmental Health News article, there is no strong evidence directly linking it to cancer. According to WebMd and EPA.gov, there is no proof that glyphosate causes or increases cancer risk. On the other hand, even though it does not cause cancer, it can be very harmful to human metabolism, liver, and kidneys, and cause celiac disease, according to The National Library of Medicine as well as WebMD. On the oat milk aspect, the article by Daily Mail includes an Environmental Health News test series where they tested fourteen different oat milk brands to only find traces of glyphosate in two, Silk and MALK brands. This makes the title misleading as it implies all kinds of oat milk include this chemical.
https://www.webmd.com/cancer/herbicide-glyphosate-cancer
https://www.epa.gov/ingredients-used-pesticide-products/glyphosate
https://pmc.ncbi.nlm.nih.gov/articles/PMC8622992/