Tokens are bearer assets that the owner has to self-custody. Since self-custody is involved, people will inevitably lose tokens, as they do base layer UTXOs. And people die too.

If statistics are available that say e.g. 2% mint tokens are lost annually, a mint could relatively safely rehypothecate (or simply pay to themselves) a known fraction of the deposited bitcoin, because they know claims for it will never be made. Especially if it's a large mint, where the actual lost token amount is unlikely to deviate much from the average.

And this could even be argued to be justifiable as a monetization model. A new take on fractional reserve banking, but with its own issues.