@Andre Polykanine I like to use app.element.io/ in firefox both on linux and windows. Thunderbird matrix support is useable too.
Element android app is verry accessible and I like it too.
There is an excelent matrix client for emacs called ement-el if you are into such things.
On linux semi accessible GTK4 based desktop client is fractal.
I don't know of any windows exclusive matrix app.