Cannot uninstall SDL Trados 2019

I currently have SDL Trados 2019 SR2 15.2.8.3007 installed. I'm trying to downgrade it to an older version (15.2.7.2849).

In order to do that, I'm trying to uninstall my current version.

However, the uninstaller gives me this error:

Setup did not complete. The error is:

Setup has detected a different version of this product already installed. If you still wish to remove or repair that version, you must use that version's installer.

However, I don't have any other versions installed. So what gives?