2 then 3 red orbs, equally spaced in a line, motionless for over an hour, then individually disappeared and reappeared for another hour

On October 1st, 2023, my partner and I arrived home at approximately 7:30pm. Upon exiting the car, I looked south from our street in the Lincoln neighborhood of West Vancouver, Washington which provides a view of downtown Portland, specifically the I-405 (aka Fremont) bridge and the Bancorp tower area. I noticed two orbs of light oddly lined up and stationary. They seemed to be somewhat flickering between white/warm white and red. I thought it was odd and pointed it out to my partner. We unloaded the car then looked closer since they were still there. I took a short video and a photo then proceeded inside to make dinner.
I had all but forgotten about the orbs of light while in the kitchen for an hour, I then went into the living room which has a window that faces south. I look and am surprised to see a third light orb has appeared, lined up with the original two, this is at 8:30pm. They were all still stationery and flashing between white and red, out of sync with one another. We observe them for about 10 minutes while trying to explain what they could be, we were observing domestic flights flying lower than the orbs.
We started watching a movie, occasionally pausing, and getting up to look out the window, they were still there for another 30 minutes, then began seeming to disappear and reappear suddenly. It was a clear night and often only one of the three would disappear. Eventually around 10:30pm they all disappeared and did not reappear from our perspective.
I posted photos to the neighborhood app Nextdoor and someone replied with a video much clearer than the ones I got of the same three orbs in the sky, the male and female heard in the video were also confused as to what they could be.
Background on us: My partner (29yo M) has a bachelor’s degree in software engineering, and I (29yo F) have a bachelor’s degree and am currently in medical school. I do not know the background of the male and female who replied with a video of the 3 light orbs to my Nextdoor post.