J1 Hiatus "Flip Flop" rule

So. I am a foreign trained Neurosurgeon, completed a one-year fellowship in the US under J1. Meanwhile, my wife (foreign trained Anesthesiologist) trained under her own J1 and is now getting a CONRAD waiver. My J1 expired in July, 2020 and I left US and re-entered under B2 (Tourist) visa, currently on B2 status. Plan to start either another fellowship or restart residency under J1 in the summer. Was told through the grapevine that ECFMG might not sponsor my J1 because I switched from J1 to B2 and now would go back to J1 (so called "Flip flop rule"), is this real? Isn't it more to do with going from J1 to another exchange or immigrant visa and then back to J1? Will I run into trouble applying for my DS-2019?