I understand what the problem is.
As I explained above, I went to the page you’ve shown in your video (test.xxxxxxx.com/genesis/), and this is what I’m seeing:
https://www.screencast.com/t/kTfSm0WxA
The code from that page is completely coming from Thrive including the paragraph style so GP doesn’t have any control over it:
https://www.screencast.com/t/wlBqnR66PKUX
This problem started when we changed theme to GP Premium when we start redesigning it
It could be that your previous theme was overwriting Thrive’s style.
Can you try activating a twenty series WP theme on the test site? I believe you would see the exact same thing as using GeneratePress.