There is a relatively common event being posted on the UFO subs on Reddit which shows the clouds being lit up by a bluish, or more commonly, purplish light. In contrast to spotlights, these appear as a large patch in the sky and don't move. They seem much more like the red or pink greenhouse lighting, but a smaller patch of the sky, purple, and generally near or in cities.

Is this some sort of new party light?

Might be grow lights for college football stadiums like Snapdragon Stadium in San Diego: https://fox5sandiego.com/news/local-news/snapdragon-stadium-pink-lights-san-diego/

Systems provided by companies like https://sglsystem.com/.

Lots of posts about it:

Huh, a more precise location than Chicago suburb from the OP would help.

There are some comments about Wrigley Field installing color-tunable LED lights for improved television coverage in 2023 and residents complaining about them being left on after games until the middle of the night, and the color sometimes being blue:

However, that doesn't immediately address why the light would only be visible on camera and not to the naked eye, but I'm seeing vague suggestions that camera sensors are more tuned to that blue range than the human eye.

Nothing definitive and it would help to have specific locations to rule Wrigley or other stadiums in or out.

(On Facebook, one of the people complaining about the blue light insists its not Wrigley field, since it's to her east and over the lake, though the home address that comes up for her unique name is two miles directly west of Wrigley.)

One candidate in that direction is the Chicago Botanical Garden Lightscape, which has plenty of up-pointing lights in suspiciously similar colors: https://www.chicagobotanic.org/lightscape

Though that's nine miles away, which seems a bit of a throw:

Though one of the collateral posters said they saw similar sky glow in Wilmington, Delaware, which has its own outdoor light festival going on:

For this blue Chicago light from seven months ago, one of the commenters said they hunted it down and this light was definitely Wrigley Field.

In the wrong direction for the OP on this one.

I'm not sure how high this type of cloud is, but when I want to visualize a projection on google maps I create a large polygon on the ground and then I set it at a certain height.

For example, this is a purple polygon above the nearby mall, at 800 meters (with a bigger grey polygon above to simulate cloudy sky)

While this is one above the botanical garden 2km in the sky

I've done no research on if the mall or one of the several big stores around the area might have some spotlights for some event.

Hmm, cloud cover at O'Hare, which is just a couple miles south of the dentist office, ranged from 1100 to 3300 feet that night, so a long range seems unlikely, and this light looks roughly 30-45 degrees off the horizon, which would put a ground source about 1 to 2 miles away at the most.

One candidate in the right direction and distance is the Nicholas Sportsplex, which has outdoor fields as well as an ice rink. Whether they had lights that might cause this radiance remain speculative...

... though they did host an adult hockey game:

But I would think a neighbor would have seen this effect before, all other things being equal.

Most of the images seem to be taken using the "night mode" on phone cameras. That mode really amplifies any colour in the sky, even when it is not visible to the naked eye. For example last month I had an alert from an aurora app saying that aurora might be visible from my location. I couldn't see anything when looking to my north but my phone in night mode picked up some pink and green colours:

one wonders what they were taking pictures of in the first place if they didn't know it was there. meaning if she couldn't see it with a naked eye, she likely wouldn't have seen it before.

Hmmm...