Oh, it's a completely ridiculous foul, no question and he deserved to go just for the insanity of it.
Is it a clear goalscoring opportunity? That's the bit I'm really not convinced by. He's outside the box, about 13 yards from the goal line and running at full speed when he goes down. The ball is not under control.
So, let's say Semedo doesn't exist here. When would the ball come under control? Probably not for another 5 yards or so, putting him about 8 yards from the goal line and still outside the area. He'd then have to turn inside and try to lift the ball over Sa from a ridiculously tight angle before the covering defenders get there.
Is it a "goalscoring opportunity"? Probably in theory, yes. Is it "clear"? No, not really at all - the xG from that position must be tiny - scoring from that position is very unlikely.