For me there is a simple test: how the algorithm decides what to put in my feed.

If the feed is made of posts belonging to the connections i follow (be it business pages or persons) in temporal order, then chances for addiction are low. If the algorithm decides for me what is relevant and from whom and in what order, then chances are high for addiction potential.

Algorithms are optimised for engagement (time spent there and interactions), not for my benefit (keeping up with my connections and interests). And they usually follow reinforcement/reward schedules -> specifically the Variable Ratio pattern. Just like gambling.

"For example, in a lab setting, this might involve delivering food pellets to a rat after one bar press, again after four bar presses, and then again after two bar presses. Gambling and lottery games are good examples of a reward based on a variable ratio schedule."

For FB, it could be how many irrelevant posts do i see before i get an update from a friend.