Project still references Unity Ads after conversion to IronSource and deletion of package

I've converted a Unity project from legacy Unity Ads to IronSource (with a Unity Ads adapter). However, Google Play still says the app references Unity Ads. I've verified that the Legacy Unity Ads package has been deleted from Package Manager and no longer shows up on the list of packages (or in manifest.json) and that Advertising is turned off in services. I've even deleted and rebuilt the Library directory and rebuilt the Visual Studio project. But Google still tells me I'm using Unity Ads and therefore am out of compliance. Where else can I look for references to this package?

I do have the Unity Ads adapter listed in the LevelPlay Integration Manager. Could that be what is causing the trouble? However, it seems unlikely that an IronSource adapter would bring in the old legacy package.

FYI, the APK does contain the file META-INF/unity-ads_release.kotlin_module that presumably is what is triggering Google's message.

Just in case anyone else runs into this - the problem turned out to be a Google Developer UI issue. The message that Google was displaying each time I uploaded a build turned out to be an old one complaining not about the current upload, but about a much older one. It appears that Google displays old and irrelevant error messages in response to every build upload until you go into your Inbox and explicitly delete them. That's why nothing I did to the upload itself made any difference.