I have just become aware of the 2020 US Religion Census, pdf available for free download:
https://www.usreligioncensus.org/node/1638
It's a lengthy read, but there's quite a lot about JWs. One quote that caught my eye in a section discussion immigration and its effect on diversification:
The Assemblies of God (1.9%), a classical Pentecostal tradition,
is among the most racially diverse religious groups in the nation.
Those affiliated are 25% Hispanic, 5% Asian, 3% Black, and 66%
White. Even more striking, the Jehovah’s Witnesses (1.9%) exhibit
high racial diversity within the American religious landscape, with
Hispanic representing 32% of their religious group, Asian Americans
6%, Black Americans 27%, and White Americans representing 36%.
I'll leave it at that, but if anyone is interested in reports like this, it's worth a look.