Prestashop 1.7 thumbnails of variants in product page

this code will display UNIQUE images of product variants images under main  image product in product page 
ested on ubuntu 20.04 LTS / Prestashop 1.7.8.7 / Php 7.4)

try to change code between 'product_images' and its end of file
YOUR_THEME_SYSTEM_PATH/templates/catalog/_partials/product-cover-thumbnails.tpl

{block name='product_images'}

{if isset($combinationImages)}

<div class="js-qv-mask mask">

<div id="product-images-thumbs" class="product-images js-qv-product-images slick-slider">

{assign 'allIds' []}

{foreach from=$combinationImages item='combination' key='combinationId' name='f_combinationImages'}

{foreach from=$combination item='image' name='f_combinationImage'}

{assign var='thumbImageId' value="{$combinationId}-{$image.id_image|intval}"}

{append var='allIds' value="{$link->getImageLink($product.link_rewrite, $thumbImageId, 'medium_default')}"}

{/foreach}

{/foreach}

{assign 'visitedImgs' []}

{foreach from=$combinationImages item='combination' key='combinationId' name='f_combinationImages'}

{foreach from=$combination item='image' name='f_combinationImage'}

{assign var='thumbImageId' value="{$combinationId}-{$image.id_image|intval}"}

{if in_array({$link->getImageLink($product.link_rewrite, $thumbImageId, 'medium_default')},$allIds)

&& !in_array({$link->getImageLink($product.link_rewrite, $thumbImageId, 'medium_default')},$visitedImgs) }

{append var='visitedImgs' value="{$link->getImageLink($product.link_rewrite, $thumbImageId, 'medium_default')}"}

<div class="thumb-container">

<img

class="thumb js-thumb img-fluid"

data-image-medium-src="{$link->getImageLink($product.link_rewrite, $thumbImageId, 'medium_default')}"

data-image-large-src="{$link->getImageLink($product.link_rewrite, $thumbImageId, 'large_default')}"

src="{$link->getImageLink($product.link_rewrite, $thumbImageId, 'medium_default')}"

alt="{$image.legend}"

title="{$image.legend}"

itemprop="image"

>

</div>

{/if}

{/foreach}

{/foreach}

</div>

</div>

{else}

<div class="js-qv-mask mask">

<div id="product-images-thumbs" class="product-images js-qv-product-images slick-slider">

{foreach from=$product.images item=image name=thumbs}

<div class="thumb-container">

<img

class="thumb js-thumb {if $image.id_image == $product.cover.id_image} selected {/if}img-fluid"

data-image-medium-src="{$image.bySize.medium_default.url}"

data-image-large-src="{$image.large.url}"

src="{$image.bySize.medium_default.url}"

alt="{$image.legend}"

title="{$image.legend}"

width="{$image.bySize.medium_default.width}"

height="{$image.bySize.medium_default.height}"

itemprop="image"

>

</div>

{/foreach}

</div>

</div>

{/if}

{/block}

Credits:
https://www.prestashop.com/forums/topic/963580-showing-thumbnails-for-all-combinations/ (duplicated thumbs are shown)