Hi @Rodrigo, thanks for the welcome and for your quick reply.
The second solution is super simple and works perfectly. Reading the official documentation I had skipped the possibility of using a JS calculation as the value of the variable. GSAP is really a great tool!
I will integrate this solution into my project to see if using ScrollTrigger with this library for smooth scrolling causes other problems.
I take this opportunity to ask you for an explanation regarding the property start: 'top top' you suggested. In the case of this animation, the effect is the same, but if another element were to be present before the #animation element, wouldn't it be more correct to use start: 0 (which coincides with the initial position of the scrollbar)? Thanks again.