I think it's just "rainy season > more people have umbrellas > more umbrellas to go missing > umbrellas are thus going missing > PSA keep track of your umbrella"
Having access to the raws that're out, as this TL is behind by quite a bit, i can tell you Suzuki is really not that big an issue dude, you're super blowing it out of proportion.
In fact, Suzuki shows up a grand total of in the next 5 chapters.