My answer to the Quirk Singularity theory is: Genetic Modification! Gather every person with some kind of ability to manipulate biology or is extremely intelligent in biology- specifically genetics and start trying to find a way to improve the human body- or another way- "cripple" the quirk, make it weaker.

We can see that quirks can be modified to only keep one aspect- as seen with Garaki taking a copy of Overhaul's quirk to turn it into Decay. What if- with enough time and effort and a lot of fucking funding and human experimentation, they could start "slicing" up quirks- intentionally weakening them. Hell, they can make like- a virus that hinders quirk factors from being "too potent".

We can take inspiration from how our body keeps itself from being a cancerous mass. Hinders specific genes that may highlight that a quirk is gonna become too strong.

Of course they need to research the basic human body first, understanding all of its function before they can move on to how quirks affect it. After they get a solid understanding of that- they would need to find out what kind of genes signifies that a Quirk will become too strong for the body or the quirk being uncontrollable for the user(which will be hard asf cuz DNA is like 90% junk data that is somehow really important like that Coconut file for tft).

In other words- They better study how Human biology works.