How do I prevent my MacBook Pro (2017) from charging (via external monitor / usb-c)?

I have a Samsung C3***WJU monitor at home and the only way I can connect my MacBook Pro (2017) with it is via the USB-C port. Unfortunately HDMI doesn't work. As usual for today's products, the monitor is able to charge my MacBook Pro without using the original Power Adapter. I know there are many people stating overcharging is no issue anymore and a thing from the past. Truth is though, I used my MacBook in this setting for about 6 months and completely destroyed my MacBook's battery life. At the end, it couldn't keep up with 60% charge of the battery and just shut down MacOS. Pretty awesome. Not. Truth to be told, I use my MacBook Pro usually in a desktop setting. Before getting this monitor, there was simply no issue when plugged in with the Power Adapter. Battery life seemed normal. That being said, I know there is no way to prevent my MacBook from charging (I honestly don't understand why Apple doesn't provide such a feature though). Now, I read in some comments that I just should use the power adapter plus the usb-c cable for the monitor and it would always choose the power adapter over the monitor's charging mode. However, I also read in an Apple comment that the MacBook would choose the one with the higher power. Looking at my situation, it would mean that my MacBook would charge via the external monitor again as the monitor provides 65W capability compared to the power adapter's 61W. So, the question is, how do I prevent my MacBook Pro from charging via the external monitor? I don't want to spend another 200+ EUR to get my battery replaced. Any ideas?

[Edited by Moderator]