The problem was not that #root had overflow-x: hidden but that this style was global for almost all tags. So I had to remove it from the MUI Tabs component children element like this :

<main>
      <Tabs
        value={currentYear}
        onChange={handleYearChange}
        variant="scrollable"
        scrollButtons
        allowScrollButtonsMobile
        sx={{
          "& *": {
            overflowX: "unset",
          },
        }}
      >
        {renderTabs}
      </Tabs>
</main>