Safari tab groups disappeared after upgrading to a new iPhone

I have made extensive use of Safari tab groups since they were introduced. Last night I upgraded to a new iPhone via the automatic iCloud backup and restore process. Today when I went to use one of my tab groups on my MacBook I discovered they were gone. After rebooting devices and disabling and re-enabling Safari in iCloud did no good, I called Apple support. After the tech had me do all those things again, he told me that tab groups were simply a convenience and were never intended to be persistent.

What? I have been paying $10 a month for years for my iCloud storage so my data would be preserved. It's aggravating enough to lose tabs for obscure websites that I spent many hours accumulating but then to be told it is my problem adds insult to injury. If I had been warned that my tab groups were going to disappear I would have bookmarked them, but how was I to know they would simply go away because I bought a new iPhone?

What I took to be a bug in the setting up of a new iPhone is apparently not. Has anyone else encountered this problem and had a different result? If so, please share your secrets. If not, be forewarned. And Apple people, if you are reading this, please do better. This has been a very un-Apple experience.