It was a yellow. The injury is an unfortunate consequence.
That is a textbook yellow card. Hard tackle, but this is a contact sport. To imply that “he knew he had just came back from an acl and intentionally tried to hurt him” is unhinged and you need to log off for a bit. Also, you can’t expect opposition players to go easy on somebody because they just returned from injury. If he wasn’t 100% full fit then he shouldn’t have played and that’s on Ange.
Devastating result, but absolutely a yellow. It was a good call. Regardless of the result, even if you think it was cynical, nothing about that challenge met any currently-written standard for a red card.
There’s a post-match thread in r/coys for a reason, and that’s an appropriate place to vent out these types of feelings with other people who actually care. Every club has devastating injuries and turns of awful luck, we’re not special. It’s irritating AF to spam self-indulgent victimhood posts like this to subs where they’re really not relevant, and it’s not healthy to get caught in an outrage loop like this (assuming you’re not trolling).
tl;dr – yellow. you’re being cringe, maybe log off for a while.