Safari 'authorized device' shows a different macOS version from the one actually running on the Mac?

When logged in to 1password.eu, I see two Authorized Devices. One is Safari, shown as "Your current device" and the other has the hostname of my Mac. Both display the same IPv6 address, which seems to belong to my Mac.

I assume the Safari session is (obviously) the 1Password browser session, while the one with the hostname of my Mac is the 1Password 7 macOS native app.

However, while the Mac session shows macOS 11.5.1 (the version of macOS I'm running), next to the Safari session is written macOS 10.15.7. Is this apparently different macOS version number normal? I'm running Safari Version 14.1.2 (16611.3.10.1.3), but this Mac came with Big Sur so it's never (as far as I know) even run macOS 10.15.7.

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1Password Version: 7.8.7
Extension Version: Not Provided
OS Version: macOS 11.5.1