@Sebastian-Roth
I just did the debug deploy.
On the target system all partitions are called /dev/sdaX.
The manual mkswap with the old uuid and the /dev/nvmeXXXX device name gave an error (device not found).
I then tried mkswap with the old uuid and with the /dev/sdaX device name and it worked!
Debian now boots correctly and finds the swap!
I will now try your fix and edit the d1.original.swapuuids to match the /dev/sdaX name to test if the deploy will work automatically again.
It is still strange to me that the two systems use different names for the devices, since both use nvme drives.
But I guess this problem will solve itself once I use 100% identical hardware.
— UPDATE —
I updated the d1.original.swapuuids, it works!