Scroll, margin-top and Chrome?

Question

css

Hello,
I need to make the side block sticky. position: fixedyou can’t do it, flexbox is everywhere and everything will crumble. I do it like this:

var anchors = {
    textEndline: document.querySelector('.longRead__text').clientHeight + +document.querySelector('.longRead__text').offsetTop,
    el: document.querySelector('.anchors'),
    height: document.querySelector('.anchors').clientHeight + 50,
    offsetTop: document.querySelector('.anchors').offsetTop - 50  // 50 is a gutter
  }

  document.addEventListener('scroll', function(e) {
    if (window.scrollY > anchors.offsetTop && window.scrollY <  (anchors.textEndline - anchors.height)) {
      anchors.el.style.marginTop = window.scrollY - anchors.offsetTop + 'px';
    }
  })

In Firefox everything works fine, in chrome - the margin "catches up" with the scroll and the block twitches.
Has anyone come across? Is it being treated?
Thank you.