Tip for Lawn Treatment Service?

We signed up for a lawn treatment service this year, never had this service before. Hours after the person applied the treatment, we got a text asking if we were satisfied with the service, and to click on a link to give the employee a tip.

Is this normal? If so, how much of a tip is appropriate? We have a half acre if that’s of any consideration.

Please don’t go after me for using a service, I’m not physically able to do this work at this time.