"Nice job" tells someone they succeeded. It does not tell them what they actually did right, which means it teaches nothing and is forgotten by lunch.
What the research says
Research on workplace recognition draws a consistent distinction between generic praise and specific recognition, generic praise, "great work," "awesome," signals only that the giver was present. Recognition that names the exact behavior and the impact it had, "the way you reframed the question in the second half changed the room," signals that the giver was actually paying attention. The second kind is what gets remembered and what actually reinforces the behavior worth repeating. The first kind fades by the next conversation.
Why the specificity is the whole mechanism
Flattery requires no attention at all, it can be said about anyone, at any time, regardless of what actually happened. A specific compliment cannot be manufactured without having actually watched what someone did, which is exactly why it lands differently and why it cannot be faked convincingly.
Where to start
Before complimenting someone's work, name one specific thing they did and the actual effect it had, not the outcome in general terms.
This costs one extra sentence and changes what the other person takes from it entirely, from a pleasant but forgettable moment into something they can actually recognize and repeat.
Reading which specific detail is actually worth naming, versus what would just sound like you are performing attentiveness, is a judgment that gets easier the more closely you actually watched. What this gives you is the reason that one extra sentence is worth the effort of noticing it in the first place.
There is a specific way to give a specific compliment without it sounding rehearsed or overly formal, and it is worth practicing before the next moment that deserves one.