It would since the app is a modified version of discord.

git not installed in ubuntu based distro was the shock for me.

Opensource is a more used term compared to foss. So popularity wise it was chosen is my guess.

Roblox is working on it there is unofficial way using grapejuice coming soon.

Flatpak and snap don't use system theme unless you tell it.

https://itsfoss.com/flatpak-app-apply-theme/

https://www.omgubuntu.co.uk/2020/06/change-snap-app-theme/amp

First are you using the latest arch iso then get that then check if there are updates for archinstall and is windows fully shutdown i.e do you have fast startup enabled or not if so disable it .

Have you tried distrobox ? That would sound more reasonable.

That is why forks like librewolf exist.

It looks like it runs in wine. https://www.reddit.com/r/scrivener/comments/102pvtk/scrivener_on_linux_abandoned/

Mint is easiest for old windows users.

Well understandable , since thats the default look. But KDE is one of the most customizable DE, you could make it look like anything you want.

You can change the kernel if you want through update manager.Linux mint doesnt always follow with ubuntu.

Endeavouros would be recommended if you like arch , if you want an rolling relase you could try Opensuse Tumbleweed, or fairly updated but stable then Fedora.