Its without a doubt a fake.
The fact it says there is 248GB free should set the alarm bells ringing.
On any drive, 256GB formatted actually leaves 238GB free for usage.
Thats all besides the fact that 256GB Micro SD cards dont exist yet. 200GB is the largest they do and legit cards of that size are a hell of a lot more than what you paid for a supposed 256gb card. You don't even need to test it, its a fake.