Adding guest users to a site - can their account access the site from any device?

If you invite users to your site as guests (people outside your organization), they're required to link a Microsoft account to login and use the site (unless you have extremely open settings and choose not to use accounts).

When a guest user creates their account and accepts an invite, can they only access the site using the device they accepted the invite on? Or can they re-use their login on multiple devices?

We had a guest user who was able to login and use our SharePoint site on one computer, but trying to login on his other laptop would throw an error. Just wondering if this is a security mechanism, to stop people sharing their accounts around on many devices?