https://www.reuters.com/world/middle...up-2023-02-01/
An unannounced inspection at Iran's Fordow Fuel Enrichment plant found the two cascades of IR-6 centrifuges enriching uranium to up to 60% purity were interconnected in a way "substantially different" to what Iran had declared to IAEA -- internal report seen by Reuters.
Cascaded centrifuges can be connected in 2 ways, series or parallel. (Retired centrifuge technician here.)
Parallel means a common output ie 60%.
Series means incremental output ie 60 -> 90%.
boom boom.