Why were these reviews declined?

That's been largely my experience, too, with submissions pending tending to be declined.  Most of mine that are accepted seem to be so automatically.

And the two reviews of mine that were rejected were for titles in the genre of "race films" from the early 20th century, so, same for me when I review such subjects.  There must be otherwise benign words that automatically trigger a requirement for IMDb staff approval or something.

Thanks for your reply. When my third review of the film "Hannah Arendt" was rejected by imdb, I protested on this board and someone, perhaps a volunteer imdb moderator, read at least one of the rejected reviews and stated that I devoted too much time to the "historical background" of the film.  In this case, it was impossible to write a meaningful review about that particular film without devoting at least a short paragraph to the historical circumstance of the Eichmann trial itself, the focal point of the entire work, especially when so many people today aren't even remotely familiar with the trial, the individual who was tried,  or the horrendous crimes charged. I may not have agreed with Ms. Arendt's opinions, at least not completely, but I objected to the censorship and condemnation of her thinking by so-called intellectuals. If you criticize academia in any way, imdb may not approve and may censor you.  What is even more offensive is the absolute garbage reviews, many silly ones, that imdb approves. Thank you again for taking the time to respond. I am sorry about your negative imdb experience.