They probably loaded up with microchips when they were available for cheaper prices,  and chip shortage is not so severe as it was few months ago, than they increased device prices a lot after that, so now they can afford to offer bigger discounts.
As much as I appreciate was Trezor has done for hardware wallets and overall Bitcoin industry, I wouldn't buy any of their devices now, even with big discounts.
I would still use them if I receive them for free, but I think there are better options on the market right now.