The post snippet displays the rest of the post as hidden text in the widget code

Can you describe the SEO problem in more details? For us more text is always better for SEO. We’ll just respect link (<a>) attributes like rel="".
It’s a Add-on for the pro version: https://github.com/tiptoppress/seo-link-extension

To shorten the hidden excerpt you can do it:

(a) More Block: https://wp-tutoring.com/using-the-more-block-in-gutenberg/
(b) Manual Excerpt: https://kinsta.com/knowledgebase/wordpress-excerpt/#manual

Sorry, i found another solution from. This poses an SEO concern at 2 levels:
1 ° It creates duplication of content: content should only be found through 1 single url
2 ° it looks like a hidden text practice: the content is invisible to users, but visible to robots

In these 2 cases, they are blocking factors for SEO

Regards