A friend of the family had a similar issue with an older awning on a used RV, I do too, that's what peaked my interest in the first place.
The existing awning was, as mentioned above, sun-faded and rotted from years of exposure. Mine is not far behind.
When he got the replacement fabric but before he installed it he took it to a place that does canvas work and boat tops and had a strip of high-quality canvass sewn along the top edge such that when rolled up nothing but boat top material is visible. The logic being when it deteriorates just it needs to be replaced not the entire awning.
It wasn't much money so I'm tempted to try it myself.