This is has been a problem for me for some time, but I use an app called Smart Wallpaper to change my background automatically, and Microsoft Launcher doesn't seem to handle it very well. The blur effect, which I have enabled and seems to work in every other scenario, does not apply when I use backgrounds set by this app. This can make content a little harder to read in the Feed or in the settings page.
The best solution would be to find a way to blur images when using third-party wallpaper apps, but another option (for me) would be to just allow us to set different cadences for rotating wallpapers. Mine is set to change every 3 hours, and I have over 50 images in the slideshow library, whereas Microsoft Launcher only allows up to 30. If this was changed, I'd no longer need a third-party app, making this whole thing a non-issue.