I love my R5 and have had absolutely no problems with it. I was a Nikon SLR and DSLR user for 40 years before switching to the R5 mirrorless. I have had zero second thoughts. I don’t know how you concluded this is a C+ camera, it is not. I’d give it A or A+!

Looks like it could be blue exhaust from the boat that was traveling on that line and is still seen in the distance? The “problem” may have absolutely nothing to do with your camera or exposure. Indeed, the camera may have captured the shot perfectly?!

SmugMug is a great photography site for your purpose. On SmugMug's site, you can create a secure site (with password) for your photos to be shared. People to whom you provide access can view thumbnails, (expandable to full size shots), and you can allow them, or not, to download the digital files in varying resolutions set by you. Viewers can have SmugMug print selected or all shots from your galleries using multiple user-specified paper or crop sizes. My prints are usually mailed within 1 day of the order. Their printing quality is great and their prices very reasonable. If you wish, you can allow your viewers to link to your shots on their FB or other social media site. Plus many more useful features that go on and on...
SmugMug is easy to use, and their customer service is absolutely superb. I have used SmugMug for many years for photo sharing and printing, and wholeheartedly recommend the site!