iPhone stuck on white screen

TLDR: Resolution - thanks to Axel Foley's advice. I resolved the white screen (and other issues described below) by force-restarting my iPhone 11 Pro.

I got this frozen White Screen issue last night for the first time in 14 years of using iPhones. I am not exactly sure why this happened. After some research, the three most commonly cited causes of a frozen white screen are:

1. Failed software updates - I updated my iPhone to the latest iOS a couple of days before. I had also mass up-dated more than 60 apps at the same time.
2. Jailbreaks - I don't jailbreak my iPhone, ever. It's too much of a risk to do so.
3. Hardware issues - My battery is due for servicing. Yesterday, during the day, I dropped my phone but it worked fine and didn't experience any issues immediately after.
4. (Bonus non-issue) Double-tap zoom - Accessibility options can be set-up such that double tapping the screen zooms into (white space on the screen in this case). In which case, just double tap until it zooms back out.

Immediately before i got the white screen, I was out on the street and it was cold out (about -3°C) and I was texting but my phone has worked fine in less than -10°C outdoor temperatures several times before, so it doesn't seem that plausible.

So, it's mostly likely due to the iOS and/or app updates that didn't update properly. After the iOS and mass app updates, my iPhone did have some unusual issues:

• Saving photos from the gallery to the iCloud Drive File was usually a breeze but it would freeze at "Processing" if it needed to download the photos/vides from iCloud but it showed no progress. But I could still kill the app and go back to home screen.
• If it did pass the processing phase, it would now be stuck in Files, where I would usually select where I want the images to be saved but now, it was stuck at a blank screen. Again, I could still kill the app and go back to home screen
• I had to restart my phone more than usual because it was stuck on something or another. Restarting it (press and holding up volume and power buttons) took significantly much longer. Say, it used to be 2-3 minutes previously, it now took 5-6 minutes.

With the frozen white screen, I couldn't restart as usual cos I can't see where the power off slider. A huge sigh of relief after I read Axel's advice to force restart restarted my iPhone and it was back to normal. Saving photos to Files works as usual. No frozen processes.