Email sent from my iCloud email has started going to everyone’s Junk
There's nothing you can do, except use a different email address.
What happened, most likely, is that some nitwit spammed from his/her me.com address (or spoofed it), and one of the commonly used spam blacklists added the entire domain. The other people will need to catch this and add your email to their personal whitelist, the details of which will depend entirely on their email provider and/or email software (depending on which one's actually doing the filtering).