TypeForm is a very buggy & very limited platform.
If you’re using TypeForm’s native integration with Airtable, make sure you’ve mapped your fields properly in TypeForm. If it doesn’t let you map to a rich text field, you’ll need to turn off the rich text in Airtable and then remap.
However, TypeForm doesn’t let you view nor edit your mapped fields after you’ve initially created your original mapping, so you’ll need to delete your entire integration and recreate it again from scratch.
If you’ll be changing your mappings frequently, your best bet is to probably use an external integration tool like Integromat, which lets you view & edit your mappings whenever you’d like — and which also supports rich text fields.
Or, even better, leave TypeForm behind and switch to a more professional form creation tool like JotForm.
In my personal opinion, TypeForm is the worst form creation tool on the market due to all of its limitations & bugs & annoyances, so I would not recommend TypeForm.
You may also want to reach out to TypeForm support about supporting rich text fields in Airtable.