Or if the build quality of their vehicles was not up to par with US regulation or the quality standards the US market is accustomed to..which seems very possible given the connotations generally shared domestically around the phrase “made in china”
In the past "made in Germany" used to have derogatory connotations due to German goods being worse than British ones too.
As for regulations, the BYD cars consistently rank very highly on the stringent Euro NCAP tests: https://www.euroncap.com/en/results/byd/seal-u/50187
You get what you pay for.
In the case of electric cars, China has their own domestic market that actually wants to drive a decent car, and so they are building for that.
BYD cars aren't particularly "cheap" in the way a "Made in China" spatula is.