CyberGene do you have many images? One problem is that Flarum must know the height of images at page load to be able to scroll to the right place. But when images are loaded externally through bbcode, markdown, or any extension that doesn't inject the image size into the page, Flarum has to assume height zero and the content will jump once the images load.
In my paid Rich Embeds extension I implemented a feature where Flarum will download each embedded images to check the width and height, then populate that value inside of the post HTML so the content doesn't jump when the images load.
A similar problem can affect other kinds of embedded content, like those added by MediaEmbed (YouTube, Spotify, etc) or code blocks which can have slight height changes after being colored client-side.
If you have scroll alignment issues but none of the content I described above, please share information about your browser and version, and your php flarum info so we can see which extensions you are using.
