https://mspoweruser.com/disable-file-explorer-ads-windows-10/

Nevertheless, if you aren’t a fan of this type of ads, you can easily disable them by following the steps below:

Open the View tab from the File Explorer’s ribbon

Click on Options to open File Explorer settings

From the Folder Options window, click on the View tab

There, you’ll need to find the “Show sync provider notifications” checkbox

Uncheck the checkbox and then save the settings by clicking OK

After that, the ads/notifications should be gone from the Explorer