https://www.gsmarena.com/motorola_moto_g42-11608.php
Keep in mind that a phone's screen is by far the most power-intensive aspect,even when idle, it involves a lot of power for light plus usage by the CPU, GPU. So something like Always On Display will of course be a low-power sleep mode disrupter,and that's significantly more power when you're actively interacting with your phone. Instead of taking a minimal amount of battery power in sleep mode, AOD requires the SoC to remain active and to actively wake the screen periodically (or frequently if you set up a lot of notifications).
https://en.wikipedia.org/wiki/Always_on_display
Still, 10% per hour does seem quite a bit more than average. I'd suspect there is a discrepancy involved, perhaps you need to isolate how much the battery is being taxed when in its sleep mode vs. sleep mode with AOD enabled. What kind of metric are you using to track your power usage? If the Settings >> Battery menu, that's more basic and rudimentary. It's OK for general usage but you'll find more extensive battery usage stats using 'Running Services' in your phone's Developer Options menu:
https://www.howto-connect.com/how-to-view-and-control-running-services-on-android/
(You do need to first enable Developer Options within your Settings menu to access Running Services. it's a menu option that includes a lot of lower level maintenance and configuration utilities that are integral to the Android OS but typically hidden by default). Anyway, there's also a 'Cached Processes' tab in Running Services to check too. That shows apps/processes left as background processes, as opposed to actively used ones. Between the two you can get a better assessment of your battery usage.than just the Settings >> Battery menu.
Another thing to be sure to look into is in Settings >> Battery menu for any kind of 'Advanced settings' submenu. It will likely show options for optimize battery usage and sleep mode optimization that might be relevant. Just curious but approximately how many apps are you allowing to use AOD?
If you can determine just which apps are really power hungry, check the Notifications menu in Settings and check the Settings/Options menu in those apps themselves. A lot of apps that need to regularly update themselves for new messages (i.e. email, social media, texting, etc.) might include options to change how often they update themselves -- i.e. if the default is every three minutes bump it up to every ten or twenty minutes.
