I've also been experiencing the disconnects with two different x15 mice for the last year or so. Currently on win11 with v1.45 firmware and lots of disconnects. In for updates.
For the couple people that have the backwards/unreliable scrolling issue, i also had that on both mice. I fixed them both by cleaning the contacts in the rotary sensor (you could also just replace the sensor for a few dollars). It's about a 15 minute repair and it's been working perfectly for months since the cleaning.
EVGA thoughtlessly stripped my link to the guide, but you can search google/reddit for "how_to_repair_an_evga_x15_scroll_wheel" to find it.