How to fix some Chinese characters that can’t be displayed in iOS 14?
Solution 1:
A device can normally only display characters which are included in the fonts installed on it. Some Chinese characters are not included in the fonts that come with MacOS and iOS, so you would need to add fonts to see them.
The one you ask about appears to be U+22bf3. You can find the number by clicking on the blank character in the Wiktionary page. This page gives info about font support.
To add fonts to iOS you can use an app like AnyFont. But whether a particular app will use such added fonts is not guaranteed.