Quantum Electrodynamics (QED) is considered the most accurate theory in the history of science. However, this precision is limited to a single experimental value: the anomalous magnetic moment of the electron (g-factor). The calculation of the electron g-factor was carried out in 1950 by Karplus and Kroll. Seven years later, Petermann detected and corrected a serious error in the calculation of a Feynman diagram; however, neither the original calculation nor the subsequent correction was ever published.Therefore, the entire prestige of QED depends on the calculation of a single Feynman diagram (IIc) that has never been published and cannot be independently verified.If this is really the most accurate and impressive prediction in the history of science, you are probably thinking that the theorists and experimentalists worked independently. Nope.
The theorists, who did it wrong, knew about the experimental value they were supposed to match. And they matched it, but the experimental value was wrong. The theoretical value happened to be also wrong in the same way. Then the experiment got redone to give a more accurate value, and an embarrassing disagreement with theory. So the theoretical value was redone, with this knowledge, and the new theoretical value matched the new experiment. The details were never published.
I have heard of experiments being cooked to match the theory. The history of this seems to be the opposite.