Hallo Paul!

 PQ> Does this make any sense to you?

Sort of.  However in this case the most important is the retention of the
trailing 0x8d byte.  Once that has been stripped then none of the four
multibyte characters are multibyte anymore and only the four leading bytes
remain.

 PQ> I can produce *.png happy snaps of these screens on demand, if
 PQ> it'll help.

I suppose it is possible help but again, in this case, there are only four
bytes that *need* to be there in order for it to be a true utf8 message. 
They can be readily searched for in a text file.  In fact for a regular
8-bit codepage the 0x8d character will also get deleted.  This is not
unique to utf8.

Het leven is goed,
Maurice

... Huil niet om mij, ik heb vi.
--- GNU bash, version 5.0.7(1)-release (x86_64-pc-linux-gnu)