[2019] Did they change the Dynamic Crosshair?

No, it wasn't changed.

I also use the one from Modstation. Ng one, though.

Which one?
Aim Dyn is green, but doesn' have numbers below.

NG and Stiv Light Dyn do have numbers above and below and work like this.
Numbers show how much time it will take for target to reach from the center of the crosshair.
Top numbers are calibrated for target going at 30 knots, pependicular to your guns botton ones for 20 knots. You make adjustments based on those two lines. Basically - you see Kongou, for example, going perfectly in parallel to you at full spee. You see how long the shell would take to reach (it's shown in the interface) and align Kongou with that number, make a correction if you see Sierra Mike (than her speed would be 31,5 knot). Then shoot.
This crosshair helps you to estimate where the target would be, but you should make corrections to targets actual speed, angle, and possible maneuvers.

If both ships move with same speed - it doesn't matter. But destroyers just tend to be much faster than 30 knots.

Maybe it would be more correct to reprhrase myself. "To my knowledge it wasn't changed."
I collect feedback, tons of it, and I read feedback collected by another people. Not me alone, though, since symmarizing is a job of game analythics team. And I haven't haven't seen anything dynamic crosshair being broken.
Maybe, maybe, with all the cnanges with 0.8.0 indeed something has happened to it, and it slipped undetected. So I'll check what's up with dynamic crosshair.

I watched it, and it's time for checking.

I watched it, and from a first glance it seems there is a problem. Information was given to people responsible for. Now we just have to wait (I'll check up on it sometime) - even though we want bugs to be fixed instantly, fix, if dynamic crosshair scaling really turns out to be a problem, wouldn't be fast, since currently there are much more pressing matters.