It doesn’t happen automatically, you’ll have to do it yourself. As of 7/11, they are removing the interest on the first £2k for Plus/Premium members.
Any normal pot = 0%
So then you can create a savings pot that currently gets 4.1% or 4.6% for Plus/Premium members. In addition to this, you can create a “Safety Net” pot which is basically the same, just with an extra prompt if you wish to remove the money.