I made a more in depth post about the IRCCM types in game, but I mentioned in it as well, well theorized it at least at first, that in rear aspect/front aspect the IRCCM with tracking supension is most vulnerable. Essentially, the flare and target IR signatures are both inside the seeker FoV because of how the geometry works out here. The IRCCM will suspend tracking as a result as a flare has entered its fov, but will not turn back on until the flare has left the fov, which takes much longer now since there is minimal angular movement from the seeker pov. Essentially the seeker will be staring at the flare very dumbly until the flare naturally falls outside the fov or burns out, giving excessive amounts of time for the actual target to move out of the missile seeker fov. Additionally, an even more harmful effect of the trackin suspension is that in rear aspect, the seeker has barely any information about aircraft heading, so it’s extra sensitive to a sudden flare’s fast movement perpendicular to the locked aircraft, slewing the seeker off the plane (into the direction of the flare), which means sometimes that the enemy aircraft doesn’t even have to move at all either. This effect is worse with the slower reaction time the tracking suspension IRCCM has, idk what they are for MANPADS, but most likely better than the 9M at 0.02s (I assume it’s in seconds at least). It might also be 0s but idk, in which case this effect plays no role, but can be induced by a wave like motion of the target while flaring.
Not like fov gating is much better in the full rear/headon aspect either, but if this is the fov gating type IRCCM is the only one you have, it still allows for the seeker to track through the flares if the target IR signature is hotter than the flare. Alas, the MIM-72G has both types, which makes it exceptionally good in side aspect, but situationally slightly worse than fov gating alone in headon/rear aspects.