Was that even a tackle? Seems to me like he was going for the ball, and the defender slid into his studs to me.
Would be an incredibly harsh red. Imagine if you did a fist pump after scoring a goal, and a defender near you jumps in and puts his face on your fist. Is that a red for violent conduct?
Studs up challenge, went over the ball when it was thereabout, always looking like he was second to the ball. That's a late, reckless and dangerous tackle. If the image below warranted a red, all while contact on the ball, then Salah deserves a red.
CLATTENBURG ON SALAH'S CHALLENGE
Mo Salah was very fortunate not to be sent off for his challenge on Porto's Danilo Pereira.
The Liverpool forward comes over the top of the ball and clearly plants his studs onto the shin of his opponent.
UEFA guidelines on this type of challenge are clear - anything with studs above the ankle is a red card.
The VAR should have sent the referee to the review area, where I am sure he would have decided that Salah should be sent off. Instead, he is free to play in the second leg.