The Pokemon Company and Niantic have temporarily disabled PokeStop Submissions in Pokemon GO.
PokeStop Submissions were made available to a few countries such as South Korea and Brazil. It isn’t rolled out worldwide yet. The reason why submissions were disabled is due to technical issues that arose in the latest update.
Due to a technical issue that arose in the most recent update, we'll be temporarily disabling PokéStop submissions in participating countries. Thank you for your patience and please stay tuned for more information.
— Pokémon GO (@PokemonGoApp) November 20, 2018