If you remember, a while back I made a fix removing the letterboxing in the remastered version of Saints Row The Third.
Then just recently I got a request for a similar solution for the original released in 2011. I don't really know how the majority of gamers feel about the remaster and whether the original is seen as being better, but I decided to look into the issue regardless.
The game scaled very differently from the remaster in that it created black bars at the cutscenes at anything but 21:9. The old patterns or their modifications wouldn't work, so my first thought was just to remove the black bars as a shader / texture. It's not the most reliable thing in the world for future updates, however, it worked better in my experiments than trying to get the game fixed via its code.
The fix is here!