Cohorts cannot be too small (or they are not published), nor too big (or they are not particularly useful for capturing a particular set of behaviors/interests). The algorithm will balance these two constraints which will lead to any individuals coming in and out of particular cohorts. The semantic meaning of a cohort will likely change over time as well. For that, FLoC is proposing adding version IDs
“Why would the cohort membership change frequently? Isn't it based on your browsing habits?” -> cohorts need to be rebalanced over time, so your cohort membership could change.
