I looked it up in the Oxford English Dictionary (via my local public library).

greenwash

verb, transitive. (a) To mislead (the public) or counter (public or media concerns) by falsely representing a person, company, product, etc., as being environmentally responsible; (b) to misrepresent (a company, its operations, etc.) as environmentally responsible.

The earliest source the OED found was in 1989, in The Daily Telegraph (London).

There’s also pinkwashing, for nominal support of the LGBTQ community or breast cancer awareness (sometimes literally just putting pink on a product). But in either case it is superficial.

A finer point - it’s mere marketing attempting to influence consumer buying decisions with platitudes that distract from pure capability evaluations or other considerations. Which obviously works on getting a lot of people over the purchasing hurdle.