Illustrations degrading

I have done a load of illustrations on my iPhone 8 and I used an app called you doodle , when I finished the illustration I saved it to photos I’ve spent the guts of 200+ hours doing them , the problem I have I’ve noticed they have degraded sufficiently, they were fine after I had saved them but over time I’ve noticed the lines disappearing and getting grainy, i have loads of storage on the iPhone as it’s 64gb and I know images degrade if you continue to save them over and over I’ve avoided doing that though and only done it the once from you doodle ,am hoping that the images will be ok on iCloud as it automatically backs my iPhone up , I haven’t got a laptop yet but will shortly , am just hoping someone will say they are ok on iCloud and will download in its original form? So much effort has been put in ,I would hate to think it’s been wasted help