Likely P&G has increased ratio of sodium percarbonate and NBOS (bleach activator) to give TwB more ooph.
P&G has long since done this for versions of Ariel powder detergent sold in EU (under various names). Those "professional" and "antibacterial" versions contain a higher oxygen bleach to activator ratio than Tide.
Ariel Professional:
https://dgduupz79pcvd.cloudfront.net/documents/fusion/fus392065msds.pdf
Regarding cold water and oxygen bleaching.
There's cold water, and there's "cold" water. Long as we're discussing cold water as say 86 degrees F to about 90 degrees F, activated oxygen bleaching systems can work rather well. Sodium percarbonate will bleach very well at lower temperatures, but exposure time might need to be increased.
In Japan cold water dominates for laundry, including whites. Yet in keeping with one of the cleanest cultures on earth, whites are often brilliant and colors quite bright.
Japanese powder detergents long ago adopted oxygen bleach and activators. Like USA NBOS is favored over TAED. This likely has something to do with like North America Japan initially favored top loading washing machines. They may have had impellers instead of central beaters, but never the less.
Ratio of oxygen bleach to activator is constant. This is because basically you're created a new chemical (peracetic acid).
Peracetic acid is a far more powerful bleach than hydrogen peroxide, but is very unstable. When bleaching activator and oxygen bleach (sodium percarbonate or perborate) are combined in water both are used up to create finite amount of peracetic acid. Thus merely adding more of one but not the other won't do much.
This means adding additional sodium percarbonate or sodium perborate neat to a detergent that already has a bleaching activator and bleach won't do much.