In the year you leave the LGPS, there is an adjustment to the pension you built up from 1 April 2014 onwards. It is revalued up to the date of leaving in line with the cost of living. Your pension fund will apply the adjustment in April after you leave. If the cost of living has gone down in the Scheme year that you leave, it is possible that the value of the deferred pension in your pension account could reduce.
For the period after your date of leaving, your total deferred benefits (including the benefits you built up before 1 April 2014) will be increased in line with the cost of living. However, if the cost of living goes down your deferred benefits will not be reduced. Your pension will also continue to receive cost of living increases every year once it is paid to you.