I've been on this train. The sound of the train being pulled onto the ferry did wake me up to say the least. It was dark outside and the blinds were shut in our sleeping coach. I remember feeling a bit of a weight, being in bed, in a closed coach, inside a large train, deep inside this massive ferry with many floors above us. It wasn't until much later that I realized that the train was open-air and not that big at all. You then wake up a few hours later near Palermo where the train runs just by the ocean – that was lovely.
I've also been on the second-to-last train of this type a few times (Snälltåget from Sweden via Denmark to Germany). That one also got canceled for the same reason – mega bridge construction (Fehmarn Belt). There, you used to get off the train to go up to the canteen for lunch with the truckers.
In the case of the Fehmarn belt it's an underwater bridge though.
I think some consider the Fehmarn Belt Fixed Link to consist of multiple parts, as the main tunnel (Fehmarn Belt Tunnel proper) is between a German island and a Danish island so stops a bit short. On the Danish side, they rebuild the Storstrøm Bridge, and on the German side they decided to build another tunnel alongside the existing Fehmarn Sound Bridge. So in total, one existing bridge, one rebuilt bridge, one short new tunnel and one long new tunnel will connect Germany proper to Denmark proper.
It was trains from Hamburg to Copenhagen used to run on the Fehmarn Ferry until the line was shut for reconstruction, they now run via Padborg.
The Snalltaget sleeper train from Berlin to Malmo used to run on the ferry from Sassnitz to Trelleborg avoiding Denmark altogether, that stopped because the ferries don't run on that route any more, and the train also runs via Padborg.