There can be many reasons for the slow download experience. It includes issues with the Microsoft Store app, enforced speed limiter on the application, corrupted Microsoft Store cache ...

The Microsoft Store is an important constituent of Windows 11 due to the coming support ... Now try to install or update the apps or download fresh apps and see if they work as they should.

Microsoft has confirmed it will soon delete an easy way users could access and download themes on Windows 11 and 10.