Debian image partitions are aligned to a 1MB boundary, while the Pi OS image partitions are aligned to 4MB boundary. The alignment is done to insure that partitions include a whole number of physical blocks which have different sizes on different media. Having a fraction of physical block inside a partition could lead to very rare problems, such as data corruption on a partition that wasn't even mounted: if you unplug the power while the physical block on the border is being overwritten, the entire block content may be lost: for a hypothetical 4MB block that could be 1 MB in the partition you were writing to and 3MB in the next partition.
I would expect Debian maintainers to do their research before choosing this boundary value, so I suggest you keep it as it is. It is very unlikely that you'll have an SD card which suffers from the problem above, because if such cards were widespread, Debian would have redefined the partition boundaries.