There are various ways to handle this.
First off there is local avoidance (which you may or may not already be using): https://arongranberg.com/astar/docs/local-avoidance.php
The easiest is probably to simply don’t order the units to the same point, instead pick points around the target point (which can be done in numerous ways). There are some built-in functions for this in the package:
I also shared another script with another user recently that does this in a different way (take a look at the linked script, it has a few comments): Which options of the asset are best for RTS (like Starcraft II)