Let's take it in pieces.
"Dynamic" generally means "(of a process or system) characterized by
constant change,
activity, or progress." But beyond that, there is
not a formal, aviation-wide definition of a dynamic maneuver. Means
slightly different things in, say, airline flight, military formation flight, or helicopter flight.
For a go-around, "dynamic" applies to the activity in the cockpit - multiple crew actions to be initiated rapidly and virtually simultaneously. Already noted.
It also refers to the
forces on the aircraft and crew -
accelerations from thust change, pitch change, speed change and altitude change. In amounts somewhat more intense and rapid than stable flight.
Regarding the latter, those accelerations can be mistaken for one another due to somatogravic illusions: if one is being pushed back in seat 0A or 0B, is that due to forward acceleration from high engine thrust in straight and level flight - OR - due to a high pitch angle (possibly even with decaying airspeed)? Or both?
They were probably a factor in the go-arounds that ended in pitchdowns right into the center of the runway
(Yeah, yeah, I know - we're supposed to be Iron-Willed Sky Gods who
never get fooled by "seat-of-the-pants" sensations and our inner ear. But we're fighting millions of years of evolution to do that - so it's still aways a risk factor).
Regarding the former - how many cases in the past few years have there been of go-arounds initiated -
and the crew forgot to, or otherwise failed to, fully activate TOGA or otherwise increase thrust, and lost speed precipitously?
Incident: Austrian E195 at Salzburg on Oct 27th 2017, go around without thrust
Or forgot to allow for pitch-up from underwing engines, and also got close to stalls?
I guess the summary would be that a dynamic maneuver is "a maneuver involving a rapidly changing situation, both as to procedures, and aircraft movements, that will require
maximum mental focus and situational awareness to accomplish successfully."