Ukraine

• Drones are cheap. Sacrificing one isn't a huge issue.

• A 1 way flight can be twice as long.

• A return flight can be tracked, and personnel are valuable.

These 3 are the main reasons. If they are striking a target in a low stakes situation, e.g. an abandoned tank, then a bomb and return is completely viable. Similar for a quick surveillance flight.

In this situation, it's likely to be spotted, and the spotters motivated to track it. It would have been a shoot and scoot launch, with nowhere to return to, rather than risk visitors, or artillery fire.