As far as I heard paper can’t be recycled because the fiber gets shorter every turn. It can be respiralled until it’s worthless pulp.

Eg:

> Fiber cannot, however, be recycled endlessly. It is generally accepted that a fiber can be used five to seven times before it becomes too short (as a result of repulping and other handling) to be useable in new paper products.

- https://archive.epa.gov/wastes/conserve/materials/paper/web/...

I thought the same about glass but that turns out to be genuinely endlessly recyclable. Good to know!