This is a shot from the interior of a car (there are several “Metrolinks”; this is in St. Louis)

I tried searching around, but couldn’t find images that looked much different for the St. Louis Metrolink.

Lambert Airport

Based on this map, it’s the Red Line.

https://www.metrostlouis.org/nextstop/contract-for-new-metrolink-light-rail-vehicles-approved/

Siemens Mobility has been a leader in intelligent transport solutions for more than 175 years and has been the exclusive provider of light rail vehicles since MetroLink began operations 30 years ago.

https://www.mobility.siemens.com/us/en/company/newsroom/press-releases/siemens-mobility-to-deliver-metro-transit-in-st-louis-with-55-s200-high-floor-light-rail-vehicles.html

Bi-State Development, which operates Metro Transit in St. Louis, has selected Siemens Mobility to design and manufacture up to 55 new hybrid battery Siemens S200 high-floor vehicles to replace its oldest light rail vehicles. For its MetroLink light rail system, Metro Transit currently operates 87 Siemens SD-400 and SD-460 light rail vehicles (LRVs) first ordered in 1990. With the oldest vehicles at the end of their lifecycle, these new S200 vehicles will offer the latest in comfort, reliability and sustainability.

So I’m guessing that it’s either an SD-400 or SD-460, and presumably there is some variation.