I'm using a laptop and have the three-finger-click trackpad set up to simulate the middle mouse button.

As shown in the video, when I close the tabs with the middle mouse button, the tabs are closed; however, when I use the middle mouse button emulated by the trackpad, the tabs are not closed (the video is of the Groupy, but I've tested the Groupy 2 with the same problem)

This is a Windows 10/11's issue. I found that it might have something to do with Windows' policy that the middle mouse button emulated by the trackpad needs to be specially adapted (my guess). For example, Microsoft Edge browser and Windows 11 File Manager both adapt the middle mouse button and the middle mouse button simulated by the trackpad, but groupy only adapts the middle mouse button, which makes it impossible to close tabs via the trackpad.

I think there are a very large number of laptop users who use three-finger stand-alone to close tabs, and this problem of yours is a direct result of the fact that I had to give up on Groupy 2, which I was going to buy on Steam. 

All in all, I hope you guys adapt the middle mouse button simulated by the trackpad.