iCloud.com

Do you own the MacBook Air and Pro? Those are the only two devices that are signed in. The line of text that your arrows are pointing to is only an explanation of what types of devices are capable of being in the list (e.g., if you had a Mac running something earlier than Yosemite, it would not show in the list with your other two devices even if it was signed in).

The previous owner who had set up iOS 8 , Mac OS Yosemite .. didn't erased the apple devices and they were are not removed from his Apple ID account , and now WKR 13 has purchased the Mac from him , even he erased the Mac OS and installed Mac OS catalina , the device will still show as they are iCloud server based .

re: "I still do not understand why it say's you are signed in and running iOS 8."

The full sentence is "You are signed in and running iOS8, macOS Yosemite, watchOS1, or later on these devices."

Note the words "or later." The two devices shown in your list are running Catalina and that qualifies for the "or later" relative to Yosemite. If you had devices running an os earlier than Yosemite, they would not show in the list below that sentence even if you were signed in on them. You don't have anything that you need to remove from the list.

You need previous owner Apple ID and password to remove the device https://support.apple.com/en-in/guide/icloud/mmfc0eeddd/icloud

Even you had erased the refurbished Mac and reinstalled the Mac OS , the previous owner devices are shown on iCloud.com , contact the previous owner to get credentials .

Agreed with you , the op should click on done ( and back screen will be visible ) and verify that is there are any other unknown devices .

In the bottom of op screen shot in my devices section , some devices are shown like iOS ( half hidden ) and still the name of op is shown so these devices are of op and some devices that are unknown of the previous owner .

I have exactly the same sentence on my account and I have no previously owned devices.

welcome !

Sorry I'm being dense. I only see 2 devices in the list and one fully visible and one mostly hidden in the window behind the list.