2022 Puzzle 4: “Initial Reaction”

Here’s contest puzzle #4. Solve using the Crossword Compiler applet below, download a PDF, or use Across Lite.
The meta is as follows: One of the letters in the grid needs to be changed to make the theme consistent. The meta answer is the theme-related word made with the change.
Submit your answer to the meta using the form on the home page.

Initial Reaction by Pete Muller