Why does the partition start on sector 2048 instead of 63?
Because your old disc was partitioned with a old utility, such as the Linux fdisk, that uselessly implemented track-alignment using the entirely fake disc geometry that you see reported, and your new disc has been or is being partitioned by a newer utility that (by default) aligns to 1MiB boundaries instead.
Further reading
- Jonathan de Boyne Pollard (2011). The gen on disc partition alignment. Frequently Given Answers.
fdisk -c=dos
You used the old DOS partition table when creating your partition. Newer versions of fdisk do not use dos compatibility mode by default.
Maybe it will be useful to add a comment here.
For LUKS partition, it is said to delete and re-create the partition at the same place, but larger before calling cryptsetup resize.
But when you created your partition long time ago, it start at the sector 63. Using fdisk, the partition will be recreated at the wrong offset, resulting in a lost partition.
I've managed to recover it using fdisk -c=dos to be able to create partition from sector 63, without troubles.