I was aware, thanks to your announcement via email, that Evernote Clipper wouldn't work in Safari 13. So, when my old Macbook Pro running 10.13.6 told me there were updates, I looked and saw there was a Safari 13 update and a Security Update. Well, I knew I didn't want Safari 13, so instead of hitting the "Update All" button, I just hit the Update button for the Security Update. Guess what! I got Safari 13 anyway! Thanks, Apple.
But seriously, Evernote: my 1Password extension works just fine in Safari 13. You really got caught napping on this one.