As mentioned in title, the UrzaGatherer Android app rotates between landscape/portrait when tilted, even if the device has "Auto-rotate screen" disabled.
I suspect this is just a general change that was made to web apps in some recent version of the Chrome/Chromium engine, but have not been able to find a way to disable it through browser settings.
Anyway, it's pretty annoying in my case, since I often like to browse through my decks/cards when lying on my side, and this auto-rotate makes it unusable.
That said, thanks to the power of browser extensions, I have found a workaround: (until a better solution is found, or the original Chromium-engine bug/change is fixed)
1) For UrzaGatherer, use an Android browser that supports extensions -- by setting that as your default browser, or using it to add a homescreen shortcut to urzagatherer.app. (I use "Kiwi Browser" personally, but Firefox should also work -- once the deck-clickability issue here is fixed anyway)
Now if you close then reopen the UrzaGatherer app/page, it will have new code present that makes it so as soon as you click something in the UI, it will lock the rotation into portrait mode.
While most users probably don't need this rotation-locking, I figured I would share the code above for those that do. (since it's quite annoying when the app rotates sideways when trying to use lying on one's side)