You mean a ticking time bomb trope. That's the universally agreed name fans gave this nonsense.
Wano was the biggest and worst example of this bullshit. Oda had the fire about to engulf the entire castle, the fire about to set off the bombs (I'd count these as separate ticking time bombs despite both being related to the Kazenbo fire), and the island about to fall too. Three examples of that trope in ONE arc.
Wano had Nine Ticking Bombs, that were Handled by Nine Key Figures clearly hinting at Void Century Events or EOS Events,
When Act 3 Started:
Kid Joined ---> He ended up being the One who sent Big Mom out of Onigashima
Denjiro Joined ---> He ended up being the One who Saved Hiyori & Killed Orochi
Jinbe Joined ---> He ended up being the One who Stopped Castle Fire
Marco Joined ---> He ended up being the One who Delayed Ice Oni Virus giving Doctors Time to Stop it
Neko Joined ---> He ended up being the One who Defeated Perospero
Izou Joined ---> He ended up being the One who Protected Robin from CP-0 & even Killed One of them
Yamato Joined ---> She ended up being the One who Stopped Kanjuro's Flame from Igniting Bombs
O-Tama Joined ---> She ended up being the One who Countered Smile Army helping save many Duels
Adult Momo Joined ---> He ended up being the One who Stopped Flying Onigashima from reaching Capital & Safely Landed it
These aren't just Time Bombs like other Arcs, They are Nine Sub-Plots meant to Foreshadow Past/Future Events,
Such as O-Tama taming Main Villain's Army being a Reference to what Poseidon did, indicating that Sea Kings were Main Villain's Army,
And Kid's Cannon & that Deep Hole is Reference to Pluton, indicating it was Used to Stop a Monster as Strong as Main Villain ... etc
EOS will Repeat History, except this time it's gonna be the Responsibility of Nine SHs.
Harley Texts mentions all of these Future Nine Time Bombs.