Canon EOS REBEL T8i Advanced User's Manual page 648

Conditions requiring card formatting
The card is new.
The card was formatted by a different camera or a computer.
The card is full of images or data.
A card-related error is displayed.
Low-level formatting
Perform low-level formatting if the card's writing or reading speed seems slow or if you
want to totally erase the data on the card.
Since low-level formatting will format all recordable sectors on the card, the formatting
will take longer than normal formatting.
During low-level formatting, you can cancel formatting by selecting [Cancel]. Even in
this case, normal formatting will already be complete and you can use the card as usual.
Card file formats
SD/SDHC cards will be formatted in FAT32. SDXC cards will be formatted in
exFAT.
Individual movies recorded to exFAT cards are recorded as a single file (without splitting
them into multiple files) even if they exceed 4 GB, so the resulting movie file will exceed
4 GB.
Caution
It may not be possible to use SDXC cards formatted with this camera in other
cameras. Also note that exFAT-formatted cards may not be recognized by
some computer operating systems or card readers.
Formatting or erasing data on a card does not completely erase the data. Be
aware of this when selling or discarding the card. When disposing of cards,
take steps to protect personal information if necessary, as by physically
destroying cards.
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