Hey, thanks for your review!
Thumbnail image and actual description text is generated via social-media metatags (OpenGraph family). I have added in last version generation of such tags, if not provided by 3rd party, to make my plugin independent from others, but you still have option to use any OG / Social-Media plugin on your taste to manage Post preview in SE and/or in TG link. Try maybe the YastSEO (i am using it in my production) or others, thay might give your option for different thumbnails.
