Let me clarify a couple details:
Do you agree, that in PnP, sorceres have two lists:
1. list of spells known
2. list of spells per day
yes/no?
Do you, when you read the quoted relevant post believe the "8th level slot" in question comes from the "list of spells per day"?
yes/no?
If the above two are yes, please explain the second one.