How do I reduce the file size of iOS scanned documents (using the Files app)
Solution 1:
This is fixed in iOS 15 - the scan sizes are adequate now:
- color ~1MB
- gray scale ~350KB
Solution 2:
As a workaround you can scan in black & white and not in colour. Then you have much more acceptable file size (~500 kB for single page).
You can also try to compress the file after scanning. (See this answer)