I thought it wasn't just a matter of valid but of identicalness. Multiple clients with identical JA4 which comprises if I'm not mistaken useragent but also other aspects of the host machine indicate that they are in fact a single user agent.
I'm sorry, I don't fully understand your question. This is what I meant by invalid: Anyone using chrome 142 has the same JA4 - I've checked across OS/devices. If you use nodeJS and set your user agent to "chrome 142" then you will have an invalid/incorrect JA4 and you'll stick out from the crowd.
