Media image is not displayed correctly depending on OS/Browser

[myagoo]

With the following widget

<a href="//pinterest.com/pin/create/button/"
  data-pin-count="beside"
  data-pin-color="red"
  data-pin-config="beside"
  data-pin-description="Bagatelle&#x20;Courchevel&#x20;ouvre&#x20;son&#x20;restaurant&#x20;d&#x2019;altitude&#x20;pour&#x20;la&#x20;saison&#x20;d&#x2019;hiver"
  data-pin-media="https://image.over-blog.com/9PNB5XybmS9KjLpakVBBtPlvisg=/filters:no_upscale()/image%2F0950871%2F20201112%2Fob_705893_bernieshot-dianepinel-bagatelle-cou.jpg"
  data-pin-url="https://www.bernieshoot.fr/2020/11/bagatelle-courchevel-ouvre-restaurant-altitude-saison-hiver.html"
  target="_BLANK"
  >
  <img src="//assets.pinterest.com/images/pidgets/pinit_fg_en_rect_red_20.png" />
  </a>

(which can be found here : https://www.bernieshoot.fr/2014/11/referencement-bernieshoot-annuaires-web.html)

If I click the generated pin button on linux firefox, a popup is opened at : https://www.pinterest.com/pin/create/button/?guid=PMRawMg08MtP-1&url=https%3A%2F%2Fwww.bernieshoot.fr%2F2020%2F11%2Fbagatelle-courchevel-ouvre-restaurant-altitude-saison-hiver.html&media=https%3A%2F%2Fimage.over-blog.com%2F9PNB5XybmS9KjLpakVBBtPlvisg%3D%2Ffilters%3Ano_upscale()%2Fimage%252F0950871%252F20201112%252Fob_705893_bernieshot-dianepinel-bagatelle-cou.jpg&description=Bagatelle%20Courchevel%20ouvre%20son%20restaurant%20d%E2%80%99altitude%20pour%20la%20saison%20d%E2%80%99hiver and the media is displayed correctly _(User-Agent: Mozilla/5.0 (X11; Ubuntu; Linux x8664; rv:84.0) Gecko/20100101 Firefox/84.0)

Whereas when I click the generated pin button on linux chrome, a popup is opened at : https://www.pinterest.fr/pin-builder/?guid=qqvBytw8ynJE-1&url=https%253A%252F%252Fwww.bernieshoot.fr%252F2020%252F11%252Fbagatelle-courchevel-ouvre-restaurant-altitude-saison-hiver.html&media=https%253A%252F%252Fimage.over-blog.com%252F9PNB5XybmS9KjLpakVBBtPlvisg%253D%252Ffilters%253Ano_upscale()%252Fimage%252F0950871%252F20201112%252Fob_705893_bernieshot-dianepinel-bagatelle-cou.jpg&description=Bagatelle%20Courchevel%20ouvre%20son%20restaurant%20d%E2%80%99altitude%20pour%20la%20saison%20d%E2%80%99hiver&method=button and the media is not displayed correctly _(User-Agent: Mozilla/5.0 (X11; Linux x8664) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36)