https://wccftech.com/2021-macbook-pro-models-feature-hdmi-2-0/

After several years, Apple has brought back the HDMI port on the 2021 MacBook Pro models. Unfortunately, what the company failed to inform customers is that the port supports the older HDMI 2.0 standard, not the HDMI 2.1 one.

If you visit the specifications page of the 2021 MacBook Pro models, Apple is using an older-generation HDMI 2.0 port instead of an HDMI 2.1 port. In case you had the intention of hooking up your brand new, shiny MacBook Pro to a high resolution, high refresh monitor and experience that extreme level of fluidity on a bigger display, you will be disappointed here. This is because the HDMI 2.0 standard is limited to 4K and up to 60Hz.