Why did you not include Signal?

I scrolled through the document and I don't see any measurements of the number of received messages - that will pretty much dominate the standby power draw of any messaging app (rule of thumb is - 1s of modem/CPU wakeup takes away 1min of standby time).

So the data can be seriously meaningless if you don't control for the amount of messages received and their interval (spread out messages hit the power draw more than batched - phones usually race to idle).

Was element (not the X version) using google play services for notifications or did you download it from F-Droid?

Signal?