“The page jumps up when clicking on buttons in a JavaScript calendar

I'm developing a calendar in vanilla JavaScript connected to a Node.js backend.

I'm having a strange bug on the frontend:

• When clicking calendar buttons, the page scrolls up,
• The calendar re-renders after each action,
• and there seems to be a problem with the DOM scrolling or re-rendering.

The calendar is dynamically rebuilt using:

• innerHTML
• createElement
• XMLHttpRequest

I've already tried:

• type="button"
• preventDefault()
• stopPropagation()

but the problem persists.

Has anyone encountered a similar bug related to re-rendering or scroll position loss?

I've attached a video of the behavior.