It’s FAQs all the way down.
Block 200001 will refer to the block produced at Slot 200001. If there is no block produced on the next Slot (200002) and there is a block produced on the slot after (200003), this next produced block is referred to as Block 200003 as opposed to 200002. This is one of the reasons why it is acceptable to refer to slots and blocks interchangeably.