I'm having trouble reconciling the increasingly high speed at the bottom of the descent. If it encountered decreasing-performance windshear, I'd expect the speed to stay low during the descent with the nose level or maybe slightly low (close to the sticker shaker at full power to minimise altitude-loss). Even if it then encountered very strong increasing-performance windshear, the speed would start increasing, but should have been controlled enough not to get so fast while still descending. The nose would still have been somewhere near the horizon and as soon as the headwind came back on, the windshear escape manoeuvre would have the nose way up.
This appears to have just nosed over, with power still on, and rapidly accelerated with a big snatch-pull to recover, as if someone has just shoved the stick forward, held it, then pulled up.
If this was caused by a microburst, unless a dry microburst, IMO the convective cloud creating it would have been obvious on the aircraft weather radar.
This is from the FR24 data CSV (Date-Time, altitude, groundspeed):
