Me and others have had these same problems for many years. I believe I have been complaining about this and the annoying malfunctioning low battery warning pop up that appears on the screen since 2018. No, there is no fix. It is unlikely Roku is going to fix this either, because they have known about it for years and nothing has changed. My guess is they don't know how to fix it, or they do but it's a design flaw in the current model remotes and Roku either because of arrogance or cost doesn't want to design new remotes.
I have come up with my own solution that works, remove the batteries from your Roku remote when you are done using your Roku. Because even if the Roku is not plugged in the remote is draining the batteries. I only put my batteries back in when using my Roku remotes and I am still getting a 100% reading in the settings for the battery level after a couple of months of using the same batteries. Two different pairs of batteries in two different remotes so it isn't a fluke.
On the other hand I have a Fire TV Cube that I got back in September of 2022, two whole years ago. I am still using the exact same batteries that came with it and have had no issues. I got another Fire TV Stick in November 2023 and also using the same batteries. The Fire TV remotes are WiFi remotes that you pair to the device just like the Roku voice remotes. But the Fire TV remotes don't suck your batteries dry when the device isn't in use and when you are using the remotes the power drain is minimal.
The bottom line is the Roku player is a good product but the remotes that control them are utter garbage. Not just because of the battery drain but also because of putting the volume and mute buttons on the right side of the remote where they can be accidentally pressed when handling the remote. The person that designed that is deeply stupid and the people who approved that design are even more stupid.
