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I don't use ecency but I know many people do.

You can view it on website as well. Just add ?history into post url. For example for your own post it would be: https://ecency.com/hive-139531/@ecoinstant/do-you-need-to-see-edits-to-a-post-or-comment?history

This is really cool

Yeah for comments the edit history would be when you view it on their profile direct.