Sorry for the delayed reply. Have you figured out what was happening since you created this thread? If not, I would check to see if the same thing happens with a default WordPress theme when comparing the different browsers.
]]>Chrom:
<div data-thumb="https://dozeclean.local/wp-content/uploads/2020/08/CAM_15-150x150.jpg" data-thumb-alt="CAM_15" class="woocommerce-product-gallery__image flex-active-slide" style="width: 554px; margin-right: 0px; float: left; display: block;">
Firefox:
<div data-thumb="https://dozeclean.local/wp-content/uploads/2020/08/CAM_15-150x150.jpg" data-thumb-alt="CAM_15" class="woocommerce-product-gallery__image flex-active-slide" style="width: 633px; margin-right: 0px; float: left; display: block;">