I am experiencing the same issue/question. All other placements of the OG share work and were tested, twitter, fb, etc. Slack is the only one right now to still give me the small thumbnail. The site I am trying to get larger is โfunsizeโ (second link) to have the large preview like โdrumrollโ link (first link in image.
Does it have anything to do with meta description length? I have large enough images for all other OG share requirements.

Also, noticed there is no favicon match either compared to the 1st link. We have a favicon in our site, so wondering how to match all of the elements in the first link in the image.
Thanks for all the help! All yaโll at webflow rock and using this forum as a reference has been a LIFESAVER.