Interesting question. The knee-jerk answer is obviously he's not tall enough to see receivers who are open in the short middle, so his Offensive Coordinators have avoided calling plays that require him to throw into that zone.
I sought out stats that would show his number of career passes into the various zones, but was unable to locate anything like that. Instead, I found a handful of sites that reveal RW's overall passing success in different parts of the field, mainly since 2017 (apparently the recording of these statistics is rather new).
From these charts I think it's fairly obvious he does not complete as many passes in the middle as elsewhere on the field. That seems to be a good reason for him to avoid these throws, but the reason he finds less success there is still somewhat of a mystery (unless you factor in his relative lack of height, and thus his unfortunate inability to see over the taller personnel bunched up directly in front of him).