My Milk Curdled??

So I've been using the same beans for the past couple weeks (Beanworks - La Pradera) lovely berry tasting stuff. Anyway I've often been pulling turbo shots (I'm using a Picopresso so this usually helps with lighter style roasts getting good flavour - 17g in 42g out, as fast as possible, slightly courser grind).

But last time I did a turbo it wasn't tasting the best so I switched back to the usual slightly finer grind, 10 sec pre infusion then pumping till 38g out (17g in). It looked (good cream) and smelled good but I didn't taste the espresso as I was having a flat white.

Heated my milk (whole dairy milk - only purchased 2 days ago, well in date) on the stove to about 70-75°C then frothed with a french press as I always do, looked great texture. Went to pour my latte are and as soon as the milk went in is curdled straight away, I wasn't sure what was happening at first, as this has never happened to me before. Anyway I reluctantly drank it anyway as I wanted the coffee but it didn't taste good, mostly acidic but also some bitterness, no defining berry or floral like flavours I've been getting previously.

What happened?? I've pulled acidic shots before but never had milk curdle in them, frankly I didn't even know that was a ring that could happen. Did I way under extract by changing my shot profile? Or something else. Just very confused overall.. Any help appreciated