If 0203A8EC+0x7B has 0x02 set, unit does not retreat before using healing item.
Routine at 0803C0C8:
If AI4 = 0x20, set bit 0x02 of 0203A8EC+0x7B.
Jump element 0x07 (08037B78) used in AI1 0x03, 0x04, 0x05:
Sets bit 0x02 of 0203A8EC+0x7B as part of the routine.
Well, that explains why AI1 0x03 and AI4 0x20 both cause movement restrictions.
AI [03,03,XX,00] = Unit retreats before using healing item.
AI [03,03,XX,20] = Unit does NOT retreat before using healing item.
While both AI1 0x03 and AI4 0x20 set the same flag, the "use healing item" routine is called before AI1 is processed.