Lags in caret display (caret does not reset on position change)

I'm using Prismjs in my React app and everything's working fine. I just have a caret display lag whenever I move it using my keyboard arrows. In standard inputs/textareas, it looks like the caret sort of "resets" its cycle when moved. But here, it just keeps on blinking at the same pace. So if you press left arrow four times in a row, you'll have to wait until the caret appears again to see your current position (which lasts something like 0.5 second). Which is kind of disturbing. Here's my code if it helps :

import { useState, useEffect } from "react";
import Prism from "prismjs";

export default function EditCode() {
  const [content, setContent] = useState("");

  const handleKeyDown = (e) => {
    let value = content,
      selStartPos = e.currentTarget.selectionStart;

    if (e.key === "Tab") {
      value =
        value.substring(0, selStartPos) +
        " " +
        value.substring(selStartPos, value.length);
      e.currentTarget.selectionStart = selStartPos + 3;
      e.currentTarget.selectionEnd = selStartPos + 4;
      e.preventDefault();

      setContent(value);
    }
  };

  useEffect(() => {
    Prism.highlightAll();
  }, []);

  useEffect(() => {
    Prism.highlightAll();
  }, [content]);
  return (
    <section className="codeGlobalContainer">
      <textarea
        className="codeInput"
        spellCheck="false"
        wrap="off"
        cols="200"
        value={content}
        onChange={(e) => setContent(e.target.value)}
        onKeyDown={(e) => handleKeyDown(e)}
      />
      <pre className="codeOutput">
        <code className={`language-javascript`}>{content}</code>
      </pre>
    </section>
  );
}

I get that there's no CSS property like caret-blinking-speed, but is there anything I could do ? Is the handleKeyDown() function the source of my problem ?

N.B. : if I select text in my textarea, using keyboard, everything's going smoothly. Likewise, if I move my cursor with my keyboard arrows and type text instantly, there's no problem neither. It's really just the display of the caret.

Edit : If I remove the pre bloc, the problem is solved and the caret returns to its basic "reset blinking cycle on move" status.

After several tests, I've found out that it's the spellCheck="false" line in my textarea that creates my problem. So it's solved for now... But I don't know why.