ALSO JENS, I accidentally found this while searching for the upvar input group to supplement my reply here, I was not up to some crazy, "hackery" stuff
After messing with more group IDs, I figured out that these are special inputs used in only one or two blocks each. I don't know where this is used, but sorry if this doesn't constitute as a valid bug
@jens only disabled it with variadic inputs (just slots like 115), but not groups (even though the first post explains how to do it using input groups instead of with metaprogramming). It also disabled all the built in variadic groups from being variadic (script vars, send data, receivers, and else if), though he didn't actually disable creating them through the gui (if you make a variadic input, send data, recievers, and conditionals (else if) are selectable under the cog > special).