I'm vegetarian and hate most foods that contain iron (e.g. tofu, lentils).
In April 2022, I tested at a ferritin level of ~11ng/mL. A year before, during April 2021, it was 16, and a year after, during March 2023, it was 28 -- which was very unexpected, as I was expecting <15. Ferritin levels can diagnose iron deficiency, so anything less than 12ng/mL is considered deficient. I probably won't put a ton of energy into eating iron-rich foods.
Any test that can diagnose iron deficiency taken in the first half of 2024 counts (beginning of Janurary 2024 to end of June 2024, which will most likely be April-ish). I'm genuinely really curious to what percentage this'll end up at, considering I couldn't find anything remotely helpful online.
("Resolves as expected")
Ideally you should post thresholds for other tests that are relevant for the judgement of 'iron deficiency' (transferrin saturation, iron levels, etc in case you do just one of those) but to be honest it is a judgement call anyway and for some of the tests there are confounding factors (eg inflammation). Threshold decisions will be a little complicated to resolve.