Channel Form template tag broken JS in EE4

At first I thought maybe this had to do with our add-ons, but I was able to reproduce this with the simplest of examples from EE Docs:

{exp:channel:form channel="main" return="contact/thanks"}
   <input name="title" type="text">
   <input name="my_custom_field" type="text">
   <input type="submit" value="Submit">
{/exp:channel:form}

I get 2 JS errors that say:

Uncaught ReferenceError: FluidField is not defined