It is on the Apple website, which I don't think anyone checked.TB5 has double the bandwidth. Use the HDMI port for one display amd you still have one high-bandwidth TB5 port remaining; that is what I do with my MBP and three 4K displays. I actually wonder if one TB5 port might drive two 4K displays.
Display Support
M4
Simultaneously supports up to three displays:
- Up to three displays: Two displays with up to 6K resolution at 60Hz over Thunderbolt and one display with up to 5K resolution at 60Hz over Thunderbolt or 4K resolution at 60Hz over HDMI
- Up to two displays: One display with up to 5K resolution at 60Hz over Thunderbolt and one display with up to 8K resolution at 60Hz or 4K resolution at 240Hz over Thunderbolt or HDMI
- Support for native DisplayPort 1.4 output over USB-C
Simultaneously supports up to three displays:
- Up to three displays: Three displays with up to 6K resolution at 60Hz over Thunderbolt or HDMI
- Up to two displays: One display with up to 6K resolution at 60Hz over Thunderbolt and one display with up to 8K resolution at 60Hz or 4K resolution at 240Hz over Thunderbolt or HDMI
- Support for native DisplayPort 2.1 output over USB‑C
- Support for one display with up to 8K resolution at 60Hz or 4K resolution at 240Hz (M4 and M4 Pro)