Given Android is not listed, I suspect the Linux cohort may just be mostly mobile.

Does this count people with uBlock origin? I'm just one data point but here is my user agent:

What is my user agent? Your User Agent is: Mozilla/5.0 (Android 10; Mobile; rv:88.0) Gecko/88.0 Firefox/88.0

According to useragent v2.2.1: ua

    rawUa: Mozilla/5.0 (Android 10; Mobile; rv:88.0) Gecko/88.0 Firefox/88.0
    string:
    family: Firefox Mobile
    major: 88
    minor: 0
    patch: 0
    device: Generic Smartphone 0.0.0

os

    string: Android 0.0.0
    family: Android
    major: 0
    minor: 0
    patch: 0

According to ua-parser-js v0.7.20: ua

    ua: Mozilla/5.0 (Android 10; Mobile; rv:88.0) Gecko/88.0 Firefox/88.0

browser

    name: Firefox
    version: 88.0
    major: 88

engine

    name: Gecko
    version: 88.0

os

    name: Android
    version: 10

device

    vendor: undefined
    model: undefined
    type: mobile

cpu

    architecture: undefined

According to platform.js v1.3.5: ua

    name: Firefox Mobile
    version: 88.0
    layout: Gecko

os

    os: Android 10

device

    product: Mobile
    manufacturer:
    description: Firefox Mobile 88.0 on Mobile (Android 10)

Yes, also before the HN peak it seemed that windows was not so common actually. Which kind of makes sense given the product.