There is a bug in sync open tabs for devices. I have only two devices laptop (windows 11, 92.0.4561.21) and an android phone (71.3.3718.67322). When sync enabled with settings to sync only Bookmarks, Tabs and History - opera creates in block Open tabs (at https://www.sync.opera.com) Device with open tab.
Fresh install for both laptop and phone (passphrase was reset at sync.opera.com), no passphrase to encrypt all data is used, only for passwords (default behavior).
Every time I quit Opera regardless of device, a new block for the same device appear in Open Tabs at sync.opera.com. So I have already more than 10 devices in synced tabs on phone, and 3 on windows PC...
P.S. Tested it with Synchronize all data (including passwords) - same.[link text](link url)