UPDATED December 10, 2021. The US Supreme Court has granted certiorari in this case.
See https://rossrunkel.com/blog/scotus-grants-certiorari-in-important-arbitration-case

Southwest Airlines has filed a petition for certiorari at the US Supreme Court in which the issue is whether workers who load or unload goods from vehicles that travel in interstate commerce, but do not physically transport such goods themselves, are interstate “transportation workers” exempt from the Federal Arbitration Act. Southwest Airlines v. Saxon [Briefs]. There seems to be a direct conflict between at least two federal Circuit Courts on this issue. The 7th Circuit holds that they are “transportation workers” exempt from the Federal Arbitration Act. Saxon v. Southwest Airlines (7th Cir 2021). The 5th Circuit holds that they are not exempt. Eastus v. ISS Facility Servs, 960 F.3d 207 (5th Cir 2020).

It's the 7th Circuit case that is awaiting the Court's decision on whether to grant review. The 7th Circuit describes the situation this way:

"Latrice Saxon is a ramp supervisor who manages and assists workers loading and unloading airplane cargo for Southwest Airlines Company. After she brought a lawsuit against her employer, Southwest invoked the Arbitration Act. Saxon asserted that she was an exempt transportation worker, but the district court found her work too removed from interstate commerce and dismissed the case.

"We reverse. The act of loading cargo onto a vehicle to be transported interstate is itself commerce, as that term was understood at the time of the Arbitration Act's enactment in 1925. Airplane cargo loaders, as a class, are engaged in that commerce, in much the way that seamen and railroad employees were, and Saxon and the ramp supervisors are members of that class. It therefore follows that they are transportation workers whose contracts of employment are exempted from the Arbitration Act."

Which ever way the Supreme Court might decide this case (assuming they decide it at all), it's important to have some uniformity around the country.