Random Trap In Basement on PVC Waste Line

I came across this random PVC trap on a waste line in the basement. It goes up to a second story full bathroom. Any idea why this would be installed down in the basement? It appears to be original to the builder, the home was built in 2004.

Either something is double trapped or the Trap is too far from the fixture it serves is how I would have worded the narrative… have a plumber further evaluate blah blah blah.

That’s a running trap. If it’s part of a waste system and not strictly condensate disposal it’s improper.