Why do so many who complete the 40 lessons, plus other training, find QSOs so hard to copy?
You are listening on the air with various interference etc
You are not interested in just one character - you have to remember what you just heard.
Some morse is not the best quality - gap size wise in particular.
There are lots of abbrevs some of which are confusing.
Some people xmit faster than they can decode - and so get blasted back with code too fast for them.
Try just listening on the air for a bit and see how you go.