Apple Mail app introduces weird character combinations and hides attachments

Has anyone resolved this issue yet?  

For me, the problem manifests as follows:

1. Someone sends me an email from a microsoft system.

2. I receive that email in Apple mail app - nothing strange, everything is normal.

3. I store that email in a folder on the server.  When I re-open that email later, strange combinations of characters are in it (seemingly randomly), and attachments that were in original email cannot be found.

4. If I log in to web mail, the strange character combinations  are not there and my attachments are clearly there.

5. I did not notice this problem before 2020. But it is happening frequently now (Nov 2020).

6. I like the Apple mail app, and whilst everyone else seems to think of it as basic, it suits me, and I have not found anything better.  But whilst I have this problem I am having to resort to using the Outlook app. (Sob 😥).

I have looked at Apple forums and a few people have had what I think is a similar problem, but those threads end with the expert saying “Please report this to Apple Support”.

So has anyone found a solution to this one yet?