I have a iMac, Big Sur 11.4, Safari 14.1.1. Bitwarden 1.26.5.
Safari extension is now missing. Was working yesterday; suddenly today it vanished from the toolbar. I won’t to Safari/Preferences/Externsions but nothing showing up there. I tried cleaning caches with Onyx, rebooted. Still missing.
I contacted Bitwarden support (and they got back to me within a half hour! Thank you) and they suggested I try installing the “Safari Technolgy Preview” version, and gave me a link to the download. I did do that and, viola, it worked! The extension installed in both Safari Technolgy Preview and my regular Safari. I don’t know why, but it worked.
(Also, I didn’t mention it before, but my iMac is a Retina 5K, 27-inch, Late 2014. So the issue is not just with the M1 Macs.)