By the letter of the law it's a red. The reason why these types of reds always seem harsh is because they're not always given (rarely in fact) and because the attacker has little option - Mane has to go for the ball there and his only focus is the ball. One interesting thing Neville said was what would have happened had Mane got the ball - at the force Ederson was travelling, it would have been just as dangerous but I very much suspect a red wouldn't have been given.
It's rare that a player karate kicks a keeper in the head and I'd very much argue that it's rarely a red. As for little options, ridiculous assessment and using Neville chatting **** to defend Mane is pretty ridiculous to. Caragher is pointing out how and why Neville is wrong, Neville has been terrible as a pundit for a couple of years. He started off well but is just a cliche ridden moron now.
If Ederson hit Mane and missed the ball it may well have been called a foul, but if you think it's the same thing you're as daft as Neville. Mane caught Ederson with his full weight in just his foot, Mane jumped in the air, he had his leg straight and his studs showing at head height. If Ederson hit Mane, it would have been pretty much full contact, chest to chest, leg to leg maybe as well. That makes for a monumentally LESS dangerous and less forceful impact. Same force being transferred via just the studs on your feet or across your entire chest, you're talking about a night and day difference, there is zero comparison in terms of the force of the impact.
Even so a genuine collision happens, contact is unavoidable, you sign up for football knowing you can get caught, but you also sign up knowing that being kicked in the face by someone running full speed and jumping with his leg outstretched is dangerous, a red card and 99% of players won't ever try such a tackle.
The idea that his focus is on the ball is null and void, is he taking part in a competitive football game, yes, thus he already knows someone is 99.9% likely competing for that ball.