Appears to be working in Firefox but at least Chrome & Safari are broken. Should be a really recent regression so very few possible changes to blame...

Easiest repo: the todo list on our homepage.

if (validatedAttributeNameCache.hasOwnProperty(attributeName)) {
    return true;
  }
  if (illegalAttributeNameCache.hasOwnProperty(attributeName)) {
    return false;
  }
  if (VALID_ATTRIBUTE_NAME_REGEX.test(attributeName)) {
    validatedAttributeNameCache[attributeName] = true;
    return true;
  }
  illegalAttributeNameCache[attributeName] = true;
  warning(
    false,
    'Invalid attribute name: `%s`',
    attributeName
  );
  return false;
}
function shouldIgnoreValue(propertyInfo, value) {