Basically, it's this: When using ISO 8859-1 charset, the character 0xa6 (¦) isn't drawn correctly. It is drawn as an "Š" character (that isn't even in ISO 8859-1!). Here's what it looks like on OS4:

And this is what it should look like:

!!! Note that this is not a font problem. It happens even when using the very same bitmap font on OS3 and OS4. On OS3 (and MorphOS) it's correct, on OS4 it isn't !!!
Here's the test text file:
https://easyupload.io/qfaigv