Random unexpected behaviour

[iosonosempreio]

Hi,
Randomly it triggers this strange behaviour. This issue is more likely to appear when you scroll the page very fast.

When the element (the one with the dark border) get fixed it move above the text, at the end, while loosing the fixed property it twitches.

Furthermore, if the page is loaded while the scroll position is not at the top, the sticky effect does not work at all.
Anyone else with this same problem?