Because there is a formula that directly or indirectly refers to itself, not necessarily M2 or J2, but also other unrelated cells, because you re-enter a formula, the formula in the whole table will be recalculated automatically, so this prompt appears.

You can ignore this prompt. If you really can't stand it, you can check the iteration operation in the option-formula and set the number of times to 1.

Of course, to avoid this problem, we should develop good formula entry habits and avoid quoting ourselves directly or indirectly.