My Xbox one S fan seems loud after it's been deep cleaned. The guy who cleaned the console...

we cannot assist with self repair

Following on from the previous replies, if your console is old and out of warranty and it's in a well-ventilated area and seems to be free of dust, sometimes cleaning it (internally) and replacing the thermal paste will fix that issue, but it should only be done if you know exactly what you're doing.

For example, I had an Xbox One X that wasn't overheating, but the fan was ramping up really loud at times. I cracked it open and found that the thermal paste was all dry and hard, so I cleaned it off and replaced it with some fresh, good quality paste, and the fan never ramped up loud again.

But yeah, only consider the above if the other advice doesn't work, if the console is out of warranty, and if you (or someone you know who can do it for you) know what you're doing.

When I clean my console I take the vents off the bottom where the hard drive is at.

Spray it out with canned air, make sure the canned air is at room temp and you hold the can upright, it helps putting it at the edge of a table so it doesn't cause the moist air.

Clean out the fan and clean out the dust this way, clean both sides. Clean it from the end and clean it from the fan, giving it small sprays.

In the Low 70's the console shouldn't be heating up at all. If this continues then it may need a professional cleaning from a licensed Microsoft Store or even be sent in for cleaning. Though most of the cleaning could be done at home with a can of air, don't
use an air compressor either because the pressure will destroy the consoles fan.

The Slim fan blows at different speeds, it all counts on how hot it is, slow is when the Console is running at a normal temp while fast is when it gets hot usually after an hour or two of gaming.

I also have a xbox one x, my fan only gets loud when i play a xbox one x enhanced game, i will say ever since i got it in a more aired out space it seems to be fine now, also make sure to clean the dust off and out of it.

I had my xbox since 2015 and I already cleaned it out. The fan starts to go faster now and it gets loud then turns off after a couple of seconds. But what do you mean where is it located.