the creator, croga's channel -    / @croga9581  

Why Tranquilizer was in the pre-qualifiers:
The signups for Season 4 were done in 2 stages, the first stage anyone could sign up and from those, the field minus 1 robot would be chosen. The second stage allowed all people who did not make it into the first stage to reapply with the same or a different robot, as well as anyone who missed the first stage entirely. Anyone who applied to this stage was to compete in the pre-qualifiers. The builder behind Tranquilizer was on an extended break and ended up missing the entire first stage of signups, and only made it back on time literally on the final day of stage 2 signups. So, as the main field was already decided, there was no option but to put Tranquilizer in the pre-qualifiers.