The billboards quoted Hamas leader Ismail Haniyeh who called him a "Martyr of Jerusalem" at his eulogy.
The Sunni Arab world reacted harshly.
Saudi journalist Muhammad Al Sheikh tweeted, "Pictures of the criminal Iranian serial killer Qassem Soleimani greet you from every direction in Gaza. The reason is because the terrorist Muslim Brotherhood Hamas is just the arm of a Persian conspirator ... and you want to liberate Palestine, traitors? "
Even within Gaza people were upset. One man ripped down one of the posters to the cheers of a crowd and the video went viral.
Hamas is still more popular in Gaza than Fatah by far, but Gazans seem to have little interest in becoming an Iranian proxy like Hezbollah or the Houthis.
Update: Hamas arrested the person who tore down the poster. (h/t Tomer)