Microsoft has released support for background effects for Teams browser clients. It seems like only Microsoft-curated background images (including blur) works and that you can’t use organization images or custom uploaded images. This might just be a timing issue and Microsoft will enable this functionality in the future. For those who like using the Teams browser client to join meetings, this is a nice solution.
A preview Teams feature allows organizations to upload approved corporate images for people to use during Teams meetings. When generally available, this feature will need a Teams advanced communications license. An organization can distribute up to 50 images, which users see ahead of Microsoft curated images and their own custom images (if they’re allowed to upload these images). However, there’s no way for an organization to force people to select one of the corporate images.