This is expected - the form itself is stored in a text format and the HTML must be processed as the form loads. We are considering ways to prevent display of the form until it is fully rendered for the future.
We are launching a public survey this week and I am getting significant blow-back from management and our communications folks about this rendering issue. We really need to display a "loading" animation or something. Displaying html text for 5-10 seconds while things load looks very unprofessional. We are a municipality and management is very sensitive to public perception. Can you think of any workarounds that could be employed? Perhaps loading and running Survey123 internally would provide greater flexibility to address?