A bare haha is a conversational dead end: polite acknowledgment, zero contribution. Sometimes it means they are busy. Repeated, it means your messages are not giving them anything to grab onto.
Do not reply to haha with another joke begging for applause. Change lanes: ask something, switch topics, or pull back and let them invest.
Chasing a flat haha with three more jokes reads as approval-seeking. Confidence means letting a weak reply sit.
Follow the haha with a real, easy question. It moves the thread from entertainment to actual connection.
If every reply is one word, match it briefly and see if they step up. Effort should be mutual or it is not worth feeding.
Sometimes busy, sometimes shy, sometimes low interest. One haha means nothing. A pattern of them means the conversation needs a new direction or less of your effort.
Try one lane change to a question or new topic. If the low effort continues, slow down and let them reach out. Interest shows up as effort.
Send messages that are easy and fun to answer: specific questions, light teases, or stories with a hook, instead of jokes that only need applause.