Brooks thought he had scored a first-half equalizer, only for VAR to rule it out due to Milos Kerkez being marginally offside.
Despite matching Liverpool for large parts of the game, two goals from Mohamed Salah ultimately decided the contest.
He told Daily Echo: “I think it's generally disappointing.
“I think on another day we could have won that game. I think they didn't have that many chances, obviously Mo Salah scores two and that's kind of the story of them.
“Even if you keep him quiet, which Milos I think did really well today, he can still pop up with two goals. So I think we're just on the unfortunate end of the result. But yeah, I think we can be proud of the performance.
“We created chances. Obviously on another day the disallowed goal might have been a goal and then it's a completely different game.
“So, I think we did well and it's all positives to take into our next one.”