I think it's Warren . T & T don't buy in the multi-billions. I believe their largest purchase was 1.1 billion .

I believe this is correct. T&T have so far only been allocated relatively minor portions of the total equity capital ( probably around $28-30b in all) and they have never before built up a position of this size this quickly.
In any case since Buffett is not going to actively manage any capital going forward, all we can learn from this is that he probably approves of the holding whoever initiated it.
Like others here, this is close to joint top holding for me after Berkshire now. I have had an IRR of just under 26% on this since 2017 which is not bad ! I have added to it in chunks all through - most recently earlier this year when it fell below $150. I once again find myself in the familiar position of having too much exposure to a single company so I doubt I will add meaningfully to the existing position soon. The price has almost doubled since April and it is still not obviously extravagantly valued compared to some of the alternatives in the market.