That sentence doesn’t make any sense though because “toxic debt” is about the debtor not the creditor- it’s about ability to repay. Everton might be 777’s toxic debt (arguably are) but not the other way around.
Financing the stadium was always going to involve taking on debt so while the debt level will be a concern, no buyer could reasonably expect to buy a club with a new 800m stadium cheap and debt free. The identity of the creditors is fairly unimportant, whoever it is any buyer coming in should intend to repay or refinance it.