I think you're right that disabling Prime Video may be the cure to the problem. I think Prime Video sets itself to be the default handler of any Prime Video links and will always open when you click one, unless it's disabled. I had a look around my tablet and I couldn't find any way to shut that feature off. It may be possible to do with ADB, but that is beyond what I know how to do.
If your current launcher allows, you could make a homescreen shortcut directly to a bookmark of Prime Video's page and it would behave more or less like an app, saving you some trouble launching it.
BTW, welcome to XDA!!