All my pdf document files in iPhone disappeared after I unsubscribed Acrobat pro

Actually my problem has not been solved yet. If possible, I hope someone could help me to investigate it.

Problem: All my pdf document files in iPhone disappeared after I unsubscribed Acrobat pro and turned back to Reader.

1. I had downloaded some pdf files (like bills, personal scan copies) in my iphone
2. I used iCloud to backup those files, and successfully restored them when I changed my new iPhone for 2 or 3 times before
3. 06-Jan 2022, I subscribed Acrobat pro for a trial 
4. 16-Jan 2022, I decided to unsubscribe the Acrobat pro
5. 12-Feb 2022, I found out all my pdf files in iPhone disappeared , but also I can't find or recover anything from iCloud
6. Adobe customer support (chat online) couldn't get my problem solved. They just repeated if I unsubscribed the Acrobat than it affect my pdf files because the creative cloud only have 2GB limit.. I've never used creative cloud and I always save my all files in iphone itself and icloud as well, that's the problem.. Adobe shouldn't move my pdf files and then make it disappear even I unsubscribed acrobat pro.