This is where I think we really need some insulin dependent T2s to comment....
AS a T1 with a bit of insulin resistance, I definitely find that I need much more insulin to reduce my levels if my bg goes high, and it seems quite happy to stick at 11 or 12 if I don't manage to chase it down.
So I can imagine that once you've got it down to saner levels then you might need less insulin to keep them there.
But the big question is why did the smaller dose of insulin work?
Some possibilities:
1 You've just recovered from a long lasting illness that you've had for the last 18 months or so. Long covid???
2) Injection site issues. Have you been injecting somewhere you had a lot of lipotrophy and just found a "good" site?
3) And this is a real stretch. If you're on lantus could you have injected lantus by mistake and had a lantus low? (On the rare occasions where I've had lantus lows it acts much faster than humalog and plummets my bg down.)
Of course, as a T2 you may or may not still be producing your own insulin so I don't know whether it's possible for your pancreas to suddenly give you an extra dose???
I assume you hadn't changed your diet at all? Lower carbs?
I must admit I'm pretty out of ideas, To repeat, I think you need input from some insulin dependent T2s who might have a better understanding of the whole insulin resistant bit.