When we merged Stretchy Paragraph and Stretchy Heading variations we didn't include an isActive prop to the default variation of paragraph and heading blocks.

This results in displaying themselves as a transform option in block switcher dropdown.

The solution might not be as simple as adding isActive: ( blockAttributes ) => ! blockAttributes.fitText, because such condition is very broad and can have conflicts with 3rd party paragraph/heading variations and would probably appear as always active (except when stretchy).

I was against this approach with the need for the hacks we have for these variations, but we might probably need another one here: https://github.com/WordPress/gutenberg/blob/trunk/packages/block-editor/src/components/block-switcher/block-variation-transformations.js#L49

--cc @jorgefilipecosta @mcsf