[dmi]

It's a phrase that's been around for years to mean "poor quality" (https://knowyourmeme.com/memes/recorded-with-a-potato). One theory behind the term is that the recording device was so bad/low-tech, it could be powered by a potato battery.

[NetMageSCW]

For smartphones, I think it has always meant you could replace your smartphone with a potato and get the same functionality.