I worked at my last job for almost 15 years.
I got another job but wanted to leave on good terms so I put in 5 weeks notice to train replacements.
It took three people to do the job I was doing by myself. I trained them and had them as ready as they could be.
During my final week on the job I had a meeting with my manager. They were taking away a $2 per hour incentive that I had as part of my pay for years. Oh but don't worry, your annual review is due and here's a 50 cent pay raise!
Looking back the only reason I can think for them to do that would be to lower my final vacation pay out. I think it might have saved the company a little over $100.
I did everything right and still got punched in the mouth on my way out.