On construction sites, I'd suspect that the problem is an awful lot of EM noise from machinery that should have been replaced or at least maintained decades ago, like mechanic spark generators/distributors from simple combustion motors or brushed electric motors (e.g. in drills).

Additionally, remote controls for cranes, concrete pumps and other machinery may be the cause, depending on the frequency bands these use. Here in Germany, it's all 433/869 MHz from what I remember from sites I worked at, but no idea about the US.

It may be motor noise but anecdotal evidence suggests that it happens even when the machines are off, eg on national holidays. Some kind of transmitter seems likely though. I know one construction site had analog video signals in the 2.4 Ghz range for their surveillance cameras. I accidentally found out when I did a range sweep on a video receiver for other reasons.

PS I am in northern Europe, not the US.

Any high power 2.4ghz transmitter will destroy Bluetooth communication, this is all in the same 2.45ghz ISM band. I guess they use some devices communicating on that band.

They certainly do - walkie-talkies!

Edit: Yes, they do exist - you can google this. But on reflection, a commenter below is probably right that it's more likely wireless security cameras, given typical site requirements (range, penetration depth)

I don't think they use the 2.4 GHz band.

https://en.wikipedia.org/wiki/General_Mobile_Radio_Service

Handhelds are usually UHF - in the 446MHz range. Do you know of personal radios that operate in the 2.4GHz unlicensed spectrum?

Drones (FPV), baby monitors to name two. I’m sure there’s more.