The Great Disruption was an event in which the Flux and the Ravagers, Swarm and Azure, successfully disrupted the flow of time by damaging the Temple of Atropos, on the planet Time. Since all time ran through the Temple, this impacted the whole of the Doctor's universe, creating incoherence, and unleashing the Time Force, which had been constrained.
From within the flow of time, anchored to Atropos, the Thirteenth Doctor was able to restore Time with the help of the Mouri, convincing them to send four of their number to replace the two that were damaged by the Flux and the two that Swarm had destroyed. Despite this, the damage had been done. Swarm declared that they had succeeded in their mission. The Time Force particles remained, even after the Temple had been restored. (TV: Once, Upon Time)
The situation in the Temple was exacerbated by the arrival of Swarm and Azure, (TV: War of the Sontarans) who had previously usurped the Temple. The two Ravagers had, like the Flux itself, been deliberately released to bring an end to this universe. (TV: Once, Upon Time) The pair killed multiple Priest Triangles and used Yasmin Khan and Inston-Vee Vinder, who had suddenly found themselves in the Temple, to access the quantum locked Mouri. Swarm killed two more and replaced them with Yaz and Vinder. (TV: War of the Sontarans)
Time ran wild, with no apparent sense to the passage of time. Bel observed day turning to night in an instant, and then back again. Various factions, whilst not fully understanding the cause of time's problems, attempted to assert control, such as the Daleks, Cybermen and Sontarans. (TV: Once, Upon Time) The Sontarans took advantage to attempt invasions of Earth's past, having occupied Liverpool in the present time period of the Flux, beginning in the Crimean War and rewrote history. The Thirteenth Doctor repelled their Crimean incursion and the Lupar Karvanista removed them from Earth entirely with a temporal implosion caused by ramming an Imperial Sontaran Time Carrier into the rest of the fleet in Liverpool. (TV: War of the Sontarans)
One notable effect of time running wild was malfunctions with the Doctor's TARDIS, (TV: War of the Sontarans) with the ship struggling to move and anomalies appearing in the control room, such as multiple doors, leaks of black ooze and spikes growing from the floor. (TV: The Halloween Apocalypse)
Particles of the Time Force were released into the universe, causing erosion to everything they touched, and leaving nothing behind. According to Swarm, this was a process called temporal destruction. Many people throughout the universe fell victim to these particles, which behaved like active predators, approaching moving targets in proximity. Bel and Joseph Williamson encountered the particles, observed their impact, and managed to avoid falling victim to them. (TV: Once, Upon Time)
Swarm summoned the Doctor to the Temple to reveal what he'd done, knowing Yaz was her companion, and prepared to expose Yaz and Vinder to full force of time in front of her. (TV: War of the Sontarans) The Doctor pre-empted him, by taking the place of a broken Mouri herself, along with her other companion Dan Lewis, and attempting to control the time storm herself. She successfully sheltered her friends within their own time streams and spoke to the surviving Mouri to devise a solution.
Inspired by glimpses of her past at the Siege of Atropos she received whilst being pulled into her own time stream, the Doctor had the Mouri hide four new Mouri within a Passenger form that Swarm and Azure had brought to the Temple. The Mouri retook their positions and released the Doctor and her friends. Just before her release, the Doctor briefly encountered a woman, who informed her this was part of a plan to destroy the universe and advised her to stop interfering.
Swarm congratulated the Doctor on repairing time, but was satisfied with the destruction he had wrought in so short a time, as the Time Force particles remained at large in the universe, as planned. (TV: Once, Upon Time) Swarm and Azure strengthened the Time Force further to form a psycho-temporal bridge to reach Division Control outside the universe. (TV: Survivors of the Flux) From Atropos, they planned to observe the end of the universe and offer up the Thirteenth Doctor as a sacrifice to the freed Eternal Time. Their plan failed when the Flux was extinguished, so Time destroyed the pair. (TV: The Vanquisher)