It looks like this has to do specifically with the Vivo OEM browser. The current Vivo is based on Chrome 87 (2020).
I ended up on some Chinese dev blogs etc detailing similar errors with the same message. Those seem to have been due to Vivo not handling new ES6 features. Not certain exactly what is not supported in the current version that's causing this.
We're looking at adding filtering around the
<anonymous> file in the stack trace since (as far as I can tell) that's always 3rd party scripts throwing up.