A few different people caught onto the fact that Blizzard, seemingly out of the blue, decided to permanently discount Overwatch this week. If you take a trip to their shop, you'll see that the company slashed the price of the game by 50%, making the regular version of Overwatch a mere $20. Meanwhile, the Legendary Edition will run you a whole $40, down only 33% from its original price tag.
Blizzard didn't really give any major notice or reasoning for the price reduction, but best guess would be that the game has been out for nearly three years and the time to mark it down and get anyone else who was sitting on the fence because of the price a chance to join in. It is a Blizzard title, so the chances of the company making an Overwatch 2 probably isn't going to happen anytime soon, as the company loves to upgrade stuff that works. So honestly, you're getting a good deal right now until the day comes they slash it down to $10.