It's usually a ventilation duct aimed at your head and blowing cold air at you the whole day. Temperature could be around 70 degrees but it gets chilly when it is blowing at you all the time.

That seems like poor design, proper ventilation shouldn’t be directly aimed at any humans. But 70 degrees seems like a very standard temperature for indoors, I wouldn’t consider that cold.

The air being blown out is colder than 70, it has to cool down all the generated heat from the people + computers.

Having been subject to bad venting systems many times in my career, I can confirm they make the workplace very unpleasant.

"very standard" is debatable - in my country there's a law limiting AC in public spaces to 27°C (with a 2 degree tolerance, so really 25°C). 70 °F would be regarded by nearly everybody as too cold

I would feel warm under such circumstances. That air is still above my preference.