Since the new version of safari released, safari have a capabilities to synchronize tab and group tab within ios devices like mac, iphone, and ipad. Due to the synchronize process your latest browsing activity might be in the process of synchronize, so it keep revert to the old browsing activity. The capabilities to synchronize tab is awesome, but this thing is pretty annoying. You could disable the synchronize of tab using the following step :
- Open your system preferences
- Click on the Apple ID (located on the top right system preferences windows)
- Click Icloud tab on the sidebar menu
- Uncheck safari
This bug might not happen if you have an good internet connection. If you dont have it, you can just disable the feature.