Jenny, maybe this will be intersting for you.
There is a website called " good on you" which rates the fashion brands in terms of their policies for planet, animal, labour, etc. Brands are rated from 1 (We Avoid) to 5 (Great),
The Cos is part of the H&M umbrella and its ethical policy has been rated as "it's a start" , level 3. Here's the link of their ethical report
https://directory.goodonyou.eco/brand/cos .
Looking at the main brands in the UK high street, few of them have been rated "not good enough" ( Zara, Mango, Next) and the majority has been rated "we avoid". Marks Spencer has been rated "good", only 1 level higher than H&M.
H&M have been working very hard to clean up their act and have made several positive changes in their supply chain, quality and the level of information that they share with the consumer.
Whilst my motto is "buy less, choose well" , I am supporting HM as I really like that they are one of the few fast fashion brands that is challenging themselves to improve at all levels and due to the high volumes, they can bring some good changes to the environment and to the people who only purchase from the high street.