In my social and professional circles, this is done either with a thumbs-up emoji or the text "OK".
It never occurred to me that a thumbs-up could be considered passive-aggressive (I still don't see how), but that seems like the sort of thing that is dependent on the exact social circle involved. You do have to conform to the communication norms of whatever group you're communicating with.
> You do have to conform to the communication norms of whatever group you're communicating with.
That's an excellent point. It does make sense to observe the way certain common forms of acknowledgement are being used within different context to understand the way that the group interprets them.
It never occurred to me that a thumbs-up could be considered passive-aggressive (I still don't see how), but that seems like the sort of thing that is dependent on the exact social circle involved. You do have to conform to the communication norms of whatever group you're communicating with.