In german, toast bread is the bread that's supposed to be toasted. Even if it's technically "sandwich". Once it's toasted, it's still toast, now toasted toast.
It probably works that way in other languages too.
It's not just Chinese though. Germans also call typical American sliced white bread 'toast' or 'toast bread' instead of the normal German word for bread (which would normally be something with a thicker crust and more oval than rectangular.
This guy's obsession of dumplings is... quite dangerous. We should lock him up, give him dumplings daily 3 times a day and make him translate this manhua and his other series.
There's also 麵包/面包 (flour bun, mian bao) as an option to refer to bread, other than 吐司 tu si. Though I don't know if using mian bao is as common in mainland