How are people using the ➕ reaction? What does it signify?

Good question, I'd like to know this, too.

My sense is that it's very similar to 👍 , but while that emoji conveys I'm good with this or I like this or something similarly capturing one's own feelings about the thing being reacted to, I take ➕ to mean something more like a flat this is good, a more objective appraisal. That's how I see it. I think some people use it to mean "+1", akin to an upvote, again meant to be devoid of association with the person reacting. I would suspect most people just have a personal / aesthetic preference (I work with someone who is a devout ✅-user, and I would love to see more amiga tick), so if they're the first to respond to something, most people will use whatever emoji they like best, be it 👍 perhaps with a skin shade, or ➕, or ☝️ / 👌 (which, hopefully, are slowly being divorced of their alt-right-y associations), or 👏 or 🎉 if some aspect of congratulation or celebration are in order. Now, if someone else has already responded, I think most people are likely to just tap whatever positive reactions are already present, even if they aren't that person's go-to emoji.

I choose ➕ for +1, as @Ivan Reese suggests one might. For unknown reasons👍 signals "it's okay with me", which is slightly different from "I agree." I found 🍰 a bit confusing at first because of the old expression "takes the cake".

Interesting. I took 🍰 as shorthand for "Sweet!" I'm shocked to learn that ☝️ has alt-right-y associations… oh, actually now that I'm scrolling through the emoji options I think I usually use 👆 for "Pay attention to this!" — is that safe? Or was it the other one… now I'm confused. Remember the days when we would just write the words of what we meant, and we didn't even have formatting. Uh, I'm getting old. Isn't it curious that on the one hand as software engineers we're thinking a lot about determinism and invariances and exceptional behavior and then at the same time we're totally fine with introducing more ambiguity by using undefined and more or less freely interpretable symbols into our language?

@Stefan wake me when we're giving compiler hints or tagging data using underspecified, ambiguous emoji :)

Like Jack when I use ➕ it is for +1, i.e. I totally agree with or I up vote. Like Stefen I didn't know the right-alt use of some emojis, and I used to use 👌 to just say "OK". And 👍 for a more general fuzzy approval/agreement/thanks. That makes me think that lately I was looking for an emoji for a simple "thank you". I thought about 🙏 but not sure if it is really appropriate.

I've seen people use 🙏 for thanks, and I personally have no issue with that (I'm a staunch atheist, so not sure if that makes me more or less likely to be bothered by it). I personally use 👏 or 🍰 for thanks.

I've been known to accidentally use 🖕🏼 instead of ☝🏼 .. 🤭

I've seen 🙏 with both senses. It is called "pray."

Lego Batman: "Thank you; pray hands, pray hands"

🙏 all!

i think of 🙏 as the word “bless” when used with eg cat memes