All new forms are to be built in Elementor instead of Ninja Forms. The forms are imported as a section template and added to a post via Elementor Blocks for Gutenberg.
After placing the block it will appear slightly offset in height. Published version will have perfect placement.
Elementor forms supports multipart forms, relies on your css from site settings and is available directly in a section or through the library.
Read more on Forms Widget here https://elementor.com/help/forms/