That is the PACKED ARRAY of 0..255 occupied 4 bytes under the old version and now occupies 16 bytes. Whilst I clearlyu have a workaround by switching from 0..255 to byte, that behaviour doesn't seem right to me.
0..255 is an enumeration, of the base type, which is a 32-bits integer on a 32-bit computer/compiler (at least with my limited knowledge of the standard)
An array of 32-bits values don't need packing, so both are the same
I wouldn't consider this a bug, I think it is a TP incompability however, though I haven't tested it under TP.