Question: Auto-scroll occurs when scrolling upward while items are dynamically appended

[tsujimic]

I'm building a chat-like UI where answers to a question are appended dynamically and displayed using Virtualizer.

While the content is still being appended, if I scroll in the opposite direction (upwards), the scroll position automatically jumps back toward the forward direction (downwards).

It's difficult to explain clearly in words, so I’ve attached a video showing the behavior.

Because the item sizes are not finalized while the data is still increasing, I suspect this might be a difficult problem to solve. However, I wanted to ask:

Is there a recommended way to handle this behavior?
Any advice or guidance would be greatly appreciated.

virtua-negative-scroll-direction.mp4

Platform

• OS: macOS
• Browser: Chrome
• Version of this package: 0.48.6
• Framework: Next.js 16.1.6

[inokawa]

I think it's not the default behavior of Virtualizer. I guess the props passed or methods used might be the cause.

Could you provide the actual code around Virtualizer?