What Prettier rule is adding {' '} between tags?

Question

With a block of TSX markup like so:

<div className='mb-2'>
  Start an <strong className='text-textblack'>Open Session</strong> by tapping "Begin Session", or choose a specific <strong className='text-textblack'>Session Topic</strong> below.
</div>

My formatting will insert {' '} like so:

<div className="mb-2">
  Start an <strong className="text-textblack">Open Session</strong>{' '}
  by tapping "Begin Session", or choose a specific{' '}
  <strong className="text-textblack">Session Topic</strong> below.
</div>

I cannot locate what rule is making this happen, but it's driving me nuts.