Not a direct answer to your question but it may help answer some questions...
When I first got my Apple Watch 3 NON-GPS last year in November (late) - my watch would end the day at 92%. The second day I could end at 40% and go on a third day without a problem. This was Watch OS 4.1? I think.
Watch OS 4.2 came out and not much changed.
Watch OS 4.3 came out and I noticed that after charging to 100% my watch would stay at 100% for 6-8 hours then drop rapidly. Also, I noticed that after weeks of usage, I could charge to 100% and it would only stay at 100% for a few hours then drop rapidly (much more rapidly) down to 0. So instead of ending the day at 92% I now end the day and overnight at 70%. The second day - 30-40%.
I don't think anything has changed - just the way that Apple reports the battery usage from 70-100%. I just charge every day now while I hit the shower and I'm always at 100% and ending my day (and overnight) at 70%.
I notice that traveling for whatever reason causes the AW to drain noticeably faster. So if I'm going internationally, I'll take a watch charging cable in my backpack with an Anker battery brick.
I noticed too that hitting 100% then rebooting the watch, I can continue to charge the watch for almost an hour additionally and it will stay at 100% longer. Again, I don't think it's anything changing, just how Apple reports the battery % (an overall estimate).
I've been part of the Apple Heart Study for 158 days (1,357 contributions). I know they had an update about a month back - maybe that is the cause for slightly worse battery life? But I just think it's the way Watch OS reports battery %.
Draining at 10% an hour does seem excessive. Have you rebooted your watch? (Hold Crown + Button when unlocked for 4+ seconds). This usually helps my watch - I do this once a week or so.
Buying an extra Apple Watch charging cable makes travel easy and allows me to have a cable at work if I want to charge it up for an after-work event. Highly recommended.