A guess.

But considering it is glycophate. Used as a weed killer and pest controller.

The only source would be cotton.

All non organic modern farms world wide use glycophate. Because plowing is considered bad for the climate. If farmers do not plow turning over the soil and releasing co2. Then the only way to prevent weeds is chemicals. Hence glycophate.

Given cotton is used mainly for clothing etc. I imagine it has lower requirements for such toxins compared to food production.

So my guess. It is believed to be all brands. The article states varicose brands were tested and all had high levels. But given the low numbers I doubt the press is confident enough to single out any of these brands.