This is definitely still an issue on the latest stable release. I don't think there's anything in the beta mentioned above that isn't in stable now. I've tried running with "LTE only" selected for both sims and it's a little better, in that it doesn't die before the end of the day, but it's not great. I used to be able to forget my charger and be fine for 3 days if I was careful and on wifi. Now being on wifi seems to have only minimal impact.
I have two sims, one e-sim and one physical sim. This isn't new, and up until whatever update caused this I was getting the multiple days of battery life described above.
I think this might be a pixel 7 specific issue. I know other GrapheneOS users on newer hardware that aren't reporting battery drain.
The systems battery usage data shows "Mobile Network" as 65% of usage currently and "GPS" as 31%, the current battery percentage is 37%. This is odd, because GPS was only active today for maybe 40min, however the GPS total under "view by systems" says it was active for 12hr 21min. I would have definitely noticed that since there's a little blue dot that appears in the status bar when it's being used, which was definitely only there when I was actively using navigation today.
I had made a note of this when I was troubleshooting before and turned off location completely for a few days but it didn't make a difference in battery usage so I thought it probably wasn't related.