I would your answer about this :
Usually the bike serial number is under the box near pedalier.
When the bike is stolen is often to delete these numbers to difficult the bike localization.
The serial number was deleted with a angle grinder, but not completely.
The depth is not superior to the depth of the troqueled numbers.
Do you consider that the bike box is unusable ?
The bike type is DH/freeride. There is no presence of defects in the aluminum welding or fisures found.
I think the manufacturer consider that place where the serial number is troquelled strong enough for that purpose.