In work chats, I love that someone will put a thumbs up on a message rather than respond. I will hover over it to see who acknowledged it.
To me it means, “what was communicated is complete. No questions. No additional feedback.”
Probably it just means, “I accept this, but don’t want to drag this out.”
I’d even love a thumbs down. It would mean, “what was communicated is complete, and I dislike it, but I need time for additional feedback.”
In that context, the amount of “Thanks” emails annoy me. I’d love an equivalent of the thumbs up.
I get too much email to follow. To the point there are a half dozen people I mark anything they seen for follow up so I don’t lose track of what they send. And easily 95% of it are things that go into folders where I never see them unless I search for them.