Unable to stop installation by clicking 'No' on the UAC window.

[Abhay Bhatt]

I have the Opera browser setup. When I double click on the executable file, the UAC window pops up, asking me whether to allow changes by this app to my computer. Even if I click on 'No', the setup proceeds anyway and completes.
Why is this happening? Is this a problem? If yes, then what can I do about it? (Bdw, this is also happening with other executables/setups)

Note- I have already tried the following:
https://answers.microsoft.com/en-us/windows/forum/windows_10-performance-winpc/unable-to-stop-installation-by-clicking-no-on-the/1f605677-063f-4c2a-9d4a-21221705b526?messageId=84813816-9d37-4ff2-8b76-d8514936af2d&auth=1