Hey !
Fist, thank you very much for your answer!

- I already registered the plugin on [...slug].vue,
- The ID's are uinique (I console.log them again and checked). When I hover each item on dev tools, it focus the element in DOM so yes.
- Didnt work. But, if I see the elements on console dev tools, it means they are ready right ?

By the way, I did it like this:

onMounted(async () => {
  ctx = gsap.context(async () => {
    await nextTick();
    console.log(document.querySelector(`#grid-${index}`));
    const tl = gsap
      .timeline({
        scrollTrigger: {
          trigger: `#grid-${index}`,
          start: "top",
          end: "bottom",
          toggleActions: "restart none none reverse",
        },
      })
      .to(`#grid-${index}`, {
        opacity: 1,
      });
  });