WhatsApp stuck on Loading... iCloud restore never completes after weeks

My previous iPhone had some issues with the Lightning port, so on July 30 I went to the Apple store, completed a full WhatsApp backup (more than 50GB) and iCloud backup (70GB) on the Apple WiFi and received a replacement phone.

I went back home, set up the new phone, connected to my WiFi network (100Mbps download) signed into iCloud and started restoring from the backup. Within less than an hour or so the phone became usable and all the apps and data continued restoring in the background. One at a time all the apps successfully completed, with the exception of WhatsApp, which showed a "half icon" with "Loading..." underneath. This phase usually takes a few seconds or minutes but, after several hours, it was still loading. I knew that restoring more than 50GB would take a while, so I patiently waited, and let it run overnight while connected to the power and WiFi.

When I woke up the next day, nothing had changed. I became a little worried, went to Settings > Apple ID > iCloud > iCloud Backup and noticed a counter that said "Restoring app data (43 GB remaining)". I left the page open for a few minutes and noticed that the counter would progressively go down to 42GB, 41GB, 40GB.... and then, at some random point, it would go back up to 68GB, with no errors or warnings. I kept looking at the screen for some time and noticed that this would keep happening continuously: the restore would continue for hours, the remaining data counter would go down and down and then at some point (always different) it would restart from 68GB.

I tried to restart the phone, use different WiFi networks, keep the phone in airplane mode (with WiFi on of course), keep VPN on or off, turn iCloud Drive off and on, and countless other suggestions I found online, but the result wouldn't change. After some days, I reluctantly reset the phone completely and restarted the whole process from scratch, in the hope that it would fix it, but the only thing I achieved was losing several days worth of text messages.

I also tried many third party apps that claim they can selectively restore WhatsApp data from an iCloud backup, such as Dr.Fone, MobileTrans, Syncios, Tenorshare iPhone Data Recovery, iMobie Phone Rescue and a few more... but they all fail, because apparently they don't support the latest encryption scheme that Apple is now using for iCloud Backups. Their websites don't mention that, but their support confirmed that.

Now, 22 days after getting this new iPhone, I am still in the same situation. In hindsight, of course, I should not have let the Apple employee take and reset my old phone before confirming the new one was setup correctly, but he insisted they couldn't do that. Not really sure why, since I'm physically in the store, in front of everyone, and they have all my information and credit card details, but that's a different question and now it's too late...

Before anyone suggests it, I can't afford to lose the 50+ GB of WhatsApp data, because they contain many very important things, including business and some communications I have to preserve for legal reasons.

Just to clarify, currently:

• WhatsApp can't be opened or deleted
• I can't perform an iTunes backup (because the iCloud restore is still running)
• the iCloud restore seems to be running forever in a loop
• everything else on the phone works perfectly and there are no errors at any point
• Settings > Apple ID > iCloud > iCloud Storage shows 56.1GB for WhatsApp
• Settings > General > iPhone Storage doesn't show WhatsApp
• The phone has 420GB available

I am thinking about doing the following, has anyone successfully tried it?

1. Stop Restoring iPhone in Settings > Apple ID > iCloud > Backup
2. Turn off iCloud Backup, to prevent the iPhone from overwriting my "good" backup from July with a new version without WhatsApp
3. Manually do an iTunes backup, just in case, to preserve recent messages, etc...
4. Manually delete the WhatsApp app
5. Manually reinstall WhatsApp
6. When you first start WhatsApp I believe (off the top of my head) that it will ask for my phone number, to confirm my identity, sending a text message
7. The next step (again, based on some old memory) is that WhatsApp will ask you if you want to restore your chat history from iCloud
8. If all that works correctly, I hope that WhatsApp will successfully download all the data from iCloud, without any losses
9. If everything is restored and all the data is right, I will then turn iCloud Backups back on

These articles describe some of the steps above, but I'm not sure I trust them and I'd rather confirm with someone who's actually done that:

https://faq.whatsapp.com/iphone/troubleshooting/cant-create-or-restore-an-icloud-backup/

https://faq.whatsapp.com/iphone/chats/how-to-restore-your-chat-history

https://drfone.wondershare.com/whatsapp/restore-whatsapp-chat-history-iphone.html

Does anyone have any successful experience with the 9 steps above?

Thanks!