Hello, sapodilla! Thanks for reaching out to Apple Support Communities.
After reviewing your post, it sounds like you are looking for help with the synced Safari tabs on your devices. We definitely understand that can be a concern and we'd love to help. The article that your question was linked from is very helpful when considering this issue: Set up and use iCloud Tabs.
As explained in the article above, seeing tabs on one device carried over to other synced devices is normal and expected behavior. Once you’ve closed them, they should be closed on those other devices, however. If that is not happening, we’d advise restarting and updating each involved device as this may be a one-time issue that can be resolved in that manner.
Please let us know if you have follow-up questions about this issue, or if the issue remains unresolved. Have a great day!