As far as I'm aware, the force part of the law doesn't specify whether it is inflicted by the defender charging forwards or the attacker charging into them, it's more about the overall severity of the impact. On that basis, there was definite force there (although IIRC Baird was also coming forwards in the tackle)
If the tackle earlier was a red, then that's a red.
Was there a world rugby circular or something to that effect? If so it's definitely in the red card region.
The March 2021 guidelines have the degree of danger as the decisive factor for a red card and Direct/indirect contact and high/low force as the consideration (This is just for clarification, I couldn't have told you this yesterday).
For Baird I think the force is definitely between low and high, Baird's only contribution is rotating his shoulder into contact, his feet are planted and he's upright, this rotation really isn't adding much. The +/- 20kg difference is what creates the recoil.
To be honest I have no idea what the state of the laws are currently, Baird's tackle is poor technique but relatively low danger imo and yellow seems appropriate.
I think the Italian tackle is better technique but with a higher degree of danger, he's low and driving as you're taught but once you get that wrong like he did you are involved in a high impact collision to the head/neck.
I think two yellows is probably where I'd want those but had it been red to Italy and yellow to Ireland it wouldn't have been inconsistent.
-------
I'm finally getting to watch the game through, I actually thought Carbery started well when playing 15 players. I'm just past the red, they're going down to 13 now, and can already see it getting scrappy. If its a case that Carbery couldn't adjust to the changing situation, even though it's substantially easier, that's worrying but not surprising given his game time at all levels. More games should naturally increase IQ and match fitness so hopefully he stays fit. And the lighter second row and back row is clearly producing worse quality ball which doesn't help.
Lowe's start is excellent, he looks assured and dangerous while Hansen appears to be able to handle the more restrictive right wing role also. I think Lowry is about to start playing ball.
The law is an ass but the ref has been handling this excellently so far. I read that he asked the TMO to check Baird's hit so if that's true then the above inconsistency can't be used against him either. I'd take him over Adamson or Gardner all day everyday.