I don't have the app but the studio says that I have it with a different signature

I'm using Android Studio 3.5 and can't install an app from it. My app is already on play store and I'm upgrading the app. It keeps saying there's a same application. Okay, so I deleted it, but it keeps saying that.

First a pop-up window saying that I will have to uninstall the existing application. I know why it happens. I develop on my laptop and my desktop at the same time so it happens all the time. And this app doesn't have my data so I've clicked okay and proceeded and there was no problem. But,

The device already has an application with the same package but a different signature. Retry

The application could not be installed: INSTALL_FAILED_UPDATE_INCOMPATIBLE

in new. And even I don't have the app, why does it say like that???

And installation is way too quick on play store. I think the app isn't deleted properly.

So basically, I have no app on the phone, the data, cache, apk, anything, but it keeps saying there is a same app with a different signature.

I have

1. Deleted the existing app and it still didn't work
2. Re-downloaded the app and ran and didn't work And as expected, it says if I wanna delete it, pushed OK. And the app is automatically deleted.
3. also adb uninstall com.~~.~~ not working
4. Set debuggable true, still not working
5. Ran on a friend's phone which already has the exact same app from the store and it works.
6. Tried to disable instant run but android studio 3.5 does not have that anymore.
7. Rebooted my phone.
8. Deleted caches of android studio and restarted it, as many as I could.
9. adb shell pm list packages -f : the package does not exist.
10. done adb uninstall com.~~.~~ and got Success code, but still not working

There's nothing wrong with codes. Build works perfect. It runs perfectly on my friend's phone.

I expect for the app to run perfectly but, the studio says

The device already has an application with the same package but a different signature. Retry

The application could not be installed: INSTALL_FAILED_UPDATE_INCOMPATIBLE

Also, installation is too slow. It wasn't slow like this.

this happen when you have multiple spaces or user in single phone, it will be helpful if you can tell about your phone model