He does also verbally disclose that neither phone was activated, so no cellular anything was happening. Just Wi-Fi. 5G will obviously bring the two closer together, but these results don't seem too far fetched given the two major factors vs. the 2020 SE:
#1 - the battery itself is physically just over 10% larger
#2 - the A15 is significantly more efficient than the A13
I would think on LTE only, the 2022 should still be more efficient with the Qualcomm hardware in there. But 5G will obviously drain it faster...
When comparing to the 12 Mini, the other thing to keep in mind is the screen. All else being the same, and doing the same activities, the 12 Mini's screen is going to draw more power every time due to the higher resolution and OLED panel (unless it was just all black all the time...). The 12 Mini's battery is only 10% larger than the SE 2022, with identical processor and RAM, but a more power hungry screen. So I think it's possible in certain use cases that the SE 2022 could actually match or slightly beat the 12 Mini.