This is wrong. Apple has designed their iPad Pro "folio" style accessories to fit multiple generations of iPad, but they break the MOST expensive iPad accessory they sell after only ONE generation? The Right Thing to Do™ is to offer GOOD trade-ins on Magic Keyboard for those who are purchasing a new iPad Pro, so they can get the one that fits the model.
If I get an iPad Pro 2021 (I'm seriously doubting it now), I'm going to get a Smart Folio and then use an external wireless keyboard. Not tidy, but at least it'll last more than a generation.
Come on, Apple! You are better than this!