PD (Power Delivery) over USB-C also stopped working on my MBP 2018 after updating to Monterey (12.0.1). I use a Philips 346P1CRH. Everything was working flawlessly with Big Sur.

After updating to Monterey 12.1 Beta 4 PD (Power Delivery) over USB-C is working again on my MacBook Pro 2018 using my Philips 346P1CRH!