[Google Pixel 3 XL Themes, Apps, and Mods] The MAZZTer:
EDIT: I believe this issue of my problem was unrelated as I am still seeing it with the modules uninstalled. I think it was just a coincidence I saw it around the same time. I suspect my actual problem is my battery undervolting at low charge or something along those lines since most of the time I've noticed it lately my battery is low. I'll probably reinstall this pack soon.

Unfortunately I had to uninstall this wonderful mod.

On my Pixel 3 XL running the latest April 2021 update I followed the directions and installed v12 with the systemui v7.

Occasionally, maybe a couple times a day, my display would freeze up. The rest of the phone continues running (I can hold power and get the rumble for the power menu) but I can't see what I'm doing so I have to try and reboot.

I can connect to adb shell but some commands such as reboot (and later I would find magisk --remove-modules) result in the terminal hanging. Not all commands did though. Killing systemui process to forceit to restart did not fix the problem. I tried adb reboot outside of adb shell and that also hung.

Tried the scrcpy desktop app for remote viewing of my phone and it hung as well (probably using adb to start its server on the phone).

Only a hard reboot with the power button worked to get me out of this state.

This only happened occasionally. No rhyme or reason to it, sometimes I was using my phone, sometimes it happened when my phone was sleeping, first time it happened in the customization app when trying to view the list of lockscreen phone options, most other times it happened when the phone is sleeping displaying the lock screen clock with ambient display.

However today it started causing this problem within seconds of finishing booting, every time. Nothing should have changed so I don't know why it's doing this now. I had to use magisk --remove-modules during boot to get my phone into a usable state, so unfortunately I am unable to collect any further information, especially since this is my daily driver.

Only other modules I had installed were to add command line tools (nano, sqlite, busybox, ssh, adb/fasboot).

One other thing I noticed is adding this module did not seem to cause SafetyNet to pass either test. However games that I know use SafetyNet such as Pokemon Go still worked, though Pokemon Go did ask me to log in through Google again so I suspect something is not working properly with the SafetyNet bypass.

After uninstalling the modules I see the same exact behavior from Pokemon Go though, including not being kicked for failing SafetyNet. So not sure if the SafetyNet fix was even working for me at all.

Also a side comment, when I was messing with alternate lockscreen clocks, I noticed it was using an ugly olive accent color instead of my chosen system accent color of purple. Could be something wrong there, maybe.

Only other weird thing I'm using is LiveBoot to have a cool boot sequence. Not sure if that would conflict since it shouldn't be touching anything your modules do. At the moment I'm not using Riru or Xposed or Gravitybox or anything like that.

I will probably try reapplying the module without the systemui bit later. Which is unfortunately since I really like the customization options. If you push out an update with fixes though I'll probably give it a try.