This random culinary blog seems to say it's kind of true that you can't preserve the original truffle through freezing, the process changes them. They compare it to freezing fresh bread - the result is safe to eat, but not the same as the original.
That's why the places which have done that to you, without you noticing or even suspecting, don't show it to you: if you see it, you'll imagine you can tell. You can't.
The difference is quite stark and easy to tell. Putting bread in the freezer results in bread that is like week-old stuff. It's absolutely not a trick of perception.
But perhaps the effect differs according to the kind of bread.
Needing special equipment or an unusual process to defrost indicates that it doesn't freeze well in the sense most people mean, but that it can be done with effort.
When I need to freeze bread, I don't bake the loaves fully first. I get them maybe 80% the way, then freeze. Then I can complete the bake after thawing.
I get reasonably decent results that way, although you can still tell.
https://blog.dibruno.com/2016/12/10/how-to-preserve-a-fresh-...