If it's an extremely polished turd does it even matter, it's still a turd in the end? I haven't played redfall but perhaps they thought it was a buggy broken release that at least had some redeeming qualities although a 7.5 is still too high for that pos but maybe that was the thought process.
If Suicide Squad is a turd, then Redfall (which I'm taking as a reference for being a recent, well-known example of a fully broken game on all levels) is like being shot in the knee and having your wallet stolen.
The kinds of games that get (and should get) scores below Redfall are the ones that belong to the league of Gollum.
Suicide Squad is certainly not a Gollum and far away from being Redfall.
Remember, Redfall was a first-person shooter with janky gameplay, dull open-world and level design, straight up broken enemy AI, bugs everywhere, technical issues and in DF's words "an unacceptable PC port".
Suicide Squad on the other hand is a serviceable open-world third person shooter that has very high production values, is well-written and has an engaging storyline. It's biggest issues are that the gameplay style chosen for the title feels a little forced given the IP that it's working with and that the pseudo-RPG and live-service elements add nothing to the experience.
Those are the reasons why you'd give that kind of game a 7 or a 6 at worst instead of a higher score, but they certainly don't justify rating it worse than, again,
a broken game and on par with freaking Gollum & Co.
