Firstly, “loop” behaviors aren’t a feature of authentic MBTI theory – although they have become somewhat popular in derivative theory strands as an explanation for certain unhealthy cognitive manifestations.
The essence of a “loop” is that an individual of any type is somehow influenced to suppress their auxiliary supportive function. In that case, the much weaker tertiary ascends temporarily in priority to interpret or feed the dominant function.
The tertiary is a much less effective function for the individual. Instead of adding clarity and balance, it can create a “feedback loop” that misinterprets the dominant function causing further confusion and unbalance. The result can become a negative spiral of interaction between the dominant and tertiary functions.
Instead of the auxiliary productively resolving an issue, the “loop” spirals an individual into an ever more unhealthy reverberation between the now flawed judging-perceiving balance.
Loops can last until you break the cycle. You need to identify why you’re suppressing the auxiliary function and/or simply escape the spiral by resting yourself… which is often achieved through positive use of your inferior function.