I don't know. I don't know that they have even done so as you've provided nothing to prove that has even occurred. And since none of us can know exactly what has happened, perhaps those devices that you've heard were replaced were done so for something completely unrelated to the coincidental fact the owner also had a Logitech Create keyboard.
Rumor and speculation are not facts. I know of no facts that Apple has replaced a device due to damage from a Logitech product. Nor do I know of any facts that Logitech has done anything similar.
Apple, to my knowledge, has never offered any sort of Apple device repair or replacement for damage caused by some other companies accessory product. That would be up to the company that made the accessory under their product warranty.
If there is a flaw with the Logitech Create, Apple would be under no obligation at all to do anything about that anyway - that would be up to Logitech. So I am skeptical that Apple actually replaced any device due to damage proven to be caused by a Logitech product. Why would they even do so? Logitech is a big company and handles its own product's warranty issues.