Teams was installed without my approval on my private unmanaged laptop running Windows 10 Professional.

If you don't have Teams yet, you are either in another rollout, you have done something to prevent it or your PC is managed by someone who have prevented it somehow. I think that covers all.

As for why I only use Windows now and then and since I have had a habit of supporting others I keep my personal Windows PCs as plain as possible so I can see what others suffer (obviously I remove nagware like McAfee and make sure spyware like Chrome isn't set as default browser but I have gone as far as to voluntarily run my PC with Norwegian language).