It’s a mixing valve. Typically used to temper down hotter water to the proper temp for a faucet.
What Ryan said ^^^^^^^^^…
That looks professional. Jeez
“I’m Thinking it could be anti-scold plumbing.”
My kids installed one under their sink and we didn’t dare scold them again.
scold
verb
- [remonstrate]( with or rebuke (someone) [angrily]
“Mom took Anna away, scolding her for her bad behavior”
I believe it is called a “Tempering valve!” Don’t make me lose my temper!
I won’t, I promise and I see the wording you have corrected. 
Your point? Doesn’t mean it is not called a tempering valve.
Not sure Bob… 
gerund or present participle: tempering
improve the hardness and elasticity of (steel or other metal) by reheating and then cooling it.
“the way a smith would temper a sword”
act as a neutralizing or counterbalancing force to (something).
“their idealism is tempered with realism”
I’m guessing they couldn’t find a plumber so the landscaper hooked that mess up…
It is a thermostatic mixing valve most likely installed for a stand alone tub with separate hot and cold tub valves. There is a Code for that.
Florida Building Code Residential P2713.3Bathtub and whirlpool bathtub valves.
Hot water supplied to bathtubs and whirlpool bathtubs shall be limited to a temperature of not greater than 120°F (49°C) by a water temperature limiting device that conforms to ASSE 1070 or CSA B125.3, except where such protection is otherwise provided by a combination tub/shower valve in accordance with Section P2708.4.
The same number correlates with the IRC and most likely your area.
Was there a standalone tub in the bathroom?
Calm down. Don’t lose your “temper.” 
Would it be easier to set the water hot water tank at 120 or less? I recommend lowering temperature on tank if it is too hot.
For many reasons, that often isn’t a great idea, and is not compliant when the local ordinances require a listed and rated device to limit max temp at fixtures.
Unless extreme, I never recommend lowering the temp. It is safer to add a Mixing/Tempering device at the point of use.
Google: Legionnaires Disease
Point well presented, in commercial plumbing applications. I just have concerns with households with small children and hot water tanks set at scolding levels, causing more problems, then they solve. Would the practice be to recommend temperature control on ever faucet? Most households would not have this upgrade.
Most households in my area have one or two devices serving the entire home, (located after the WH), one to the kitchen and another to all the bathrooms.
Apparently Ohio is way behind, and in new construction, or existing homes rarely observed in my home inspections. I have only seen this in commercial applications restaurant, hotels.
I will start adding it to my recommendations when I do no see it.
Thanks!
Brian Hill
Professional Master Home Inspector
InterNACHI OH license 2019005340
Hill Home Inspection LLC
(330) 503-2888
Not less than 120 in my opinion. That should be the minimum.
Many people set the water heater higher in order to get more hot water capacity at the faucets, especially with electric water heaters that take longer to recover. You are mixing it down with cold water using the faucet handle. The end result is more usable hot water capacity.
Also, many people are on load control programs. The water is only heated at night or during off-peak times. That is my set-up. The water is heated pretty high (not sure of the exact temp) overnight in a super-insulated Marathon water heater. Then it is mixed down directly out of the water heater for distribution to the fixtures. This gives us the capacity to get through the day on a single tank of hot water. Then it is re-heated overnight for the next day. Usually this set up also uses a very large water heater. Our is 100 gallons or so. With that and the mixing valve, we have never ran out of hot water on the program, even when we had five of us living here.