Uneven Unsupported vertical diagonals  

It looks like you are right at the limit for unsupported overhangs.  If you could bring it back nearer to 45 degrees you should get away with it, otherwide you'll have to enable supports.

Cheerio,

RE:

I can certainly try that, thanks.

But both angles are the same, left side and right side, why would the results be so different on the same part?

RE: Uneven Unsupported vertical diagonals

The difference probably comes from the direction of cooling airflow. I suppose your y-axis is left/right in the picture. You could try to turn the model 90 degrees, cooling from the side. This may give you a consistent result on the two slopes.

As it approaches the gap the head stops excluding just after the end of the layer below - the extrusion is still adhering to the filament just laid down.  As it approaches the far side of the gap the head begins extruding just before the start of the layer below - but there is nothing already extruded to stick to until it has moved on a little.  You are trying to print in mid air.

Cheerio,

RE: Uneven Unsupported vertical diagonals

It looks to me like it should print fine; I can routinely print steeper than 45 deg (with PLA, anyway...).  But @Diem 's last remark got me thinking...  It looks like on the left slope the nozzle travels out to the edge, across the edge, and then back; this would give you a smooth, partially supported structure on which to lay down the filament.  What is the nozzle doing on the right side?  Is it starting to print right at the edge, instead of approaching it from the right?  If so, I would try to find a way to prevent it from starting there.  I don't know how to do that off-hand, but one way might be to force the seam to be someplace else using the seam painting tool in prusa-slicer; I've never used it, so can't speak from experience.