I dealt with moving blocks a few times this year. Finding the block it get’s attached to can be a bit of trial and error.
To make changes to the Product Page XML Blocks, you’ll need to create/edit the following file:
app/design/frontend/THEME/CHILD_THEME/Magento_Catalog/layout/catalog_product_view.xml
Then (as I mentioned), it’s a bit of trial and error. I’d start by inserting the afformentioned lines into the <body> section of that file:
<referenceBlock name="product.info.details">
<block class="Bss\ProductImagesByCustomer\Block\SliderTabProduct" ifconfig="bss_product_image_by_customer/bss_product_image_by_customer_general/enable" name="bss_productimagesbycustomer_tab" template="Bss_ProductImagesByCustomer::SliderTabProduct.phtml" group="detailed_info"/>
<arguments>
<argument translate="true" name="title" xsi:type="string">SliderTabProduct</argument>
<argument name="sort_order" xsi:type="string">60</argument>
</arguments>
</referenceBlock>
It’s also best to turn of FPC, Layout and Block HTML output caches during testing so that you don’t have to keep refreshing the cache to test changes.
Those are the only tips I have for you.