Anyone ever hear of this directive regarding your lawn?

Here’s some information on cinch bugs and treatments.

You paid for this service? If so, or if he was an exterminator, he should provide you with written information, especially since it’s poison.

I’m guessing he sprinkled Diatomaceous earth on your grass to kill the cinch bugs. That is a common, relatively nontoxic agent. The material is made from diatoms which have sharp edges to small critters.
You want the dust to remain “dusty” as long as possible so it covers as many of the pests as possible. If it gets wet it clumps and loses its effectiveness.

Of course he might have used something else but I would start there.

@LuckyGuy In my area they use granulated limestone ( Diatomaceous earth ) for infestations. Some places they use a powered limestone with tobacco dust mix.

For this application DE is a great choice. It is non-toxic and does the job. You can even buy food grade if you like.
If the problem persists.you can always step it up with other chemicals but I’m guessing this will do it.

Is there anything that @LuckyGuy doesn’t know? (sigh)

Years ago I actually had a restricted pesticide.license.