Microsoft is putting a lot of effort into improving Edge Chromium with as many features as possible, and soon history and open tabs sync will be available on the popular browser.
One thing that is really important about web browsers is that they should offer synchronization functions. Google Chrome offered great advances in that sense, and today practically all browsers try to offer a reasonably unified experience.
- Google will solve high RAM consumption of Chrome in Windows 10
- Google Chrome Cleanup is an integrated anti-malware tool developed by ESET
- Chrome Actions: Type commands in the address bar to quickly execute actions
Microsoft is bringing history and open tabs sync to Edge browser
Microsoft Edge will be able to sync both the history and the open tabs at any given time. Microsoft is doing some kind of A/B test to check the operation of open tabs and history synchronization in Edge Chromium. Having a plan B makes sense if they want the operation to be optimal in all cases.
We are talking about a feature where Microsoft will have to provision and deploy the cloud infrastructure necessary for it to work. So this process may be taking place gradually because the infrastructure needs to manage the new functions.

An important aspect is that the version of Edge Chromium that has started to receive this feature is the stable one (it already started to be seen in Edge Chromium Canary in October), which means Microsoft has not added feedback gathering features about the new functions.