The Reward Selection Popup is way too narrow to provide an overview of existing Rewards. On channel without Sub, I am able to see 3 in a row and 2 rows in total (with a minor cut already on the bottom). With a sub on a channel, the lower row is not readable anymore.

My suggestion is to
a) make the popup simply bigger / higher. I've selected it, my intention is to view it, so make it viewable.
b) make the popup resizable. There is no need to "find the perfect height" now. Let each change it to their liking. It does not have to be remembered, but it would be a plus.