Google Docs: harper UI flickers on every character

**Describe the bug**
The underlining and highlighting of words flickers everytime a new character is added.

**To Reproduce**
Steps to reproduce the behavior:
1. Go to Google Docs
2. Type a target word that triggers harper
3. Type new characters
4. Existing highlights and underlines flicker

**Expected behavior**
The existing highlights and underlines should not flicker.

**Platform**
Google Docs.

**Additional context**
Add any other context about the problem here.

Reproduce the problem in Google Docs by typing a target word that triggers Harper, then adding characters and observing the existing highlights and underlines. Locate the Google Docs highlighting and underlining integration in the repository and trace how updates are applied after each character. Done means existing highlights and underlines remain stable while new text is typed.

Written by the indexing model from the issue text.