It's a jumbo pillow case!
And in this....case...it's for a Body Pillow. This is a larger than usual, long style pillow that is used to keep the arms and legs apart for people who sleep on their side. You can also lay against such a pillow and not roll out of the bed. This is the first (known) example of a Sonic theme for one of these specialty pillows. It is 20 x 54 inches.
This is a Wal Mart item in Fall 2021. The dot says 'super soft'. It is nice, bright and colorful with fun CG action poses for Knuckles, Sonic & Tails. Their background is also CG, a Green Hill sort of look. A band of blue checkers goes across the bottom, with the modern logo in the corner.

This is made by "Franco" company and should be about 6.88, which is pretty reasonable. It is 100% polyester, which means it'll probably last basically forever under normal wash / use.
You could probably also pin this up on a wall some where as a long type of wall-scroll or tapistry type decor if you didn't have such a large pillow.