Which release number of Office?
You can see that by going to File > Account > About Word in the desktop application.

I assume you are using the desktop application and not the inferior web app.

You are apparently not alone in seeing this. See:
While dictating the words appear then disappear. - Microsoft Q&A

I am not seeing this in 365's desktop application version 2508. Here is text that was picked up from the Newshour broadcast tonight:

Jared Kushner southeastern US could be spared from the worst of tropical storm Imelda this week thanks to another Atlantic system that may draw it out to sea and close some offices and schools in the Bahamas it's also last Cuba where at least one person has died it's expected to strengthen into a hurricane joining major hurricane Umberto which is farther out in the Atlantic and Umberto could actually be a saving grace with its size and force acting to pull Imelda away from the US still officials are warning residents not to take the potential impact of Imelda lightly the storm will likely linger in hazardous conditions on the coast they continue throughout the end of the week so if you're visiting the beaches please stay out of the water this week the folks in the east just be aware that flash flooding may happen in your community although the US should be largely spared the same cannot be said for Bermuda both storms are heading toward the island territory America was set to wrap around and pass north of the area tomorrow and Wednesday Bermuda head on as a strong hurricane around midweek European leaders today celebrated the results of this weekend's elections in Moldova which handed the pro western governing party a clear majority in parliament French German and Polish officials congratulated Moldova for a peaceful election despite what they called Russia's quote vote buying schemes and disinformation located between Ukraine and EU member Romania Moldova has seen as a geopolitical battleground between Russia and Europe it applied to join the EU in 2022 after Russia invaded Ukraine Moldovan president Maya sandu says russia denies interference and

I observed the grey text with changes accepted.