The end of the world has a pretty much precise definition.
It is not 90% casualties. It is 100% casualties.
Toba or its clone is not obligated to take place in any particular time frame. All it’s obligated to do is generate 90% casualties. Which has happened and can happen.
I’ll have to go back and check the numbers but I’m pretty sure if the time frame had enabled plague to reach the Western hemisphere, it probably could have managed 90%. The year of numbers are usually quoted as 40%, but that constrains a timeline in and of itself. The more clear numbers are from England and the clergy at individual villages. Rather a lot of that record keeping noted deaths in the village that grew and grew and then the records stopped because there was no one left to record. Very common to achieve 100% deaths in individual villages but, like the Irish potato famine, there was frantic emigration as well as death.
The population of Europe did not recover from plague until Columbus returned from the new world with potatoes. The ultimate prepping.
Nobody really knows what stopped it, either. The concept of burning out is always popular, but that’s just words that mean we don’t really know what stopped it.
Are you AI perhaps?
How many R's are in the word "Strawberry"?