Deleting files on SD card does not free up space on SD card I'm facing this issue:

When I delete a big folder, it's not deleted, but moved in "system data" instead, I remove the card, I plug it in my pc and my pc says that the device has to be checked for errors, it runs the check and then creates a folder named found.000, if I delete this, the free space is regained! I've already formatted my SD card, same issue happened!

The strange thing is that this happens only with large/huge files and folders, if I delete some megabytes, not a byte is added in system data! so I think I need to think why could this be happening with large data

I've got a similar 1 gb of data in internal too but this should be the mi cloud backup?
is it stored locally?
how can I delete it?
(I'm root)
Connect your SD card to PC/laptop and perform a chkdsk repair