Do battery-cycles count if I have dual-boot and I'm on Windows?

Doesn't matter that you are using Windows (I'm assuming via Boot Camp), your Mac should be able to keep track of its battery charging cycles, regardless if you boot into Windows or macOS.

There could be a number of reasons that the battery may be having issues, regardless of the cycle count. Which exact model is your MacBook Pro? Is the battery the original one that came with it or is it a replacement?

As you can imagine, it is always possible that your notebook's battery is defective. It would be rare that the battery status would be incorrect, but that could be feasible as well. Regardless, I suggest you contact Apple Support directly to see what they think and any further actions to take. You can do so simply by selecting the "Get Support" link in the upper right-hand side of this forum's web page.

yonadavmunk wrote:

Boot Camp indeed.

MacBook Pro (13-inch, 2017, Two Thunderbolt 3 ports), 2.3 GHz Dual-Core Intel Core i5, 8 GB 2133 MHz LPDDR3.

Original battery.

What made me suspicious is the low number of power cycles. I'm using this MacBook for almost over 3.5 years now.

I have mid 2012 I used everyday until April 2020

It just started showing service battery w/ cycle count of 461 and 8 years of use as my daily driver.

Y0u can prolong the life expectancy of the battery—following the general rule:

If you are near the mains leave it plugged in, if you need portability then run on battery.

Batteries can fail at any time, yes you have an expected 1000 cycle count, but it does not always pan out that way.

Get help with your Mac notebook battery

Learn how to optimize the life of the battery in your Mac notebook, fix battery issues, and get service.

https://support.apple.com/en-us/HT204054

Batteries - Maximizing Performance - Apple

https://www.apple.com/batteries/maximizing-performance/

Determine battery cycle count for Mac notebooks

https://support.apple.com/en-us/HT201585

Mac notebook computers with an Intel processor use battery health management, a feature designed to improve the lifespan of your computer's battery.

ref: About battery health management in Mac notebooks— introduced with macOS10.15.5

https://support.apple.com/en-us/HT211094

Learn how to get your Mac fixed and how much it will cost. https://support.apple.com/mac/repair/service

Get your Mac ready for service - Apple Support https://support.apple.com/en-us/HT209095

See if you qualify:

13-inch MacBook Pro (non Touch Bar) Battery Replacement Program- October 2016 and October 2017

https://support.apple.com/13inch-macbookpro-battery-replacement