I just got 'upgraded' from a SP3 to a SP7 and the 6 year old Surface Pro 3 still had at least twice the battery life. Something doesn't seem correct with the Surface Pro 7: we've been buying Surface Pro's for awhile now and the SP7 is the first time we've run into the battery falling substantially short of advertised. I've never had to worry about tweaking settings or getting through a day with a Surface Pro.
Something isn't right. I'm lucky to get 3 hours of video conferencing out of the new SP7 and have reinstalled the OS and firmware twice (nothing helped).
I hate to say that with video conferencing that's about what i get - maybe a bit more 4-5 hours max. I think it's the quad core processor and the high Res screen that really pushes it. Are you using an app or in the new Chromium Edge?