i use it more for others rather than the op, like i put an informative reaction to something to say "this was informative so if you see this reaction and havent read what they said you probably should" or smthn like that, but ig its also a way of saying "thank you for the info it was helpful" to the op, ive never considered it sarcastically or mean spiritedly. the thumbs up is more for when i agree with smthn or i like what someone said like for example an opinion, which to me is different than smthn informative or factual. ive said informative too much now it doesnt feel like a word lol