The public service pension scheme that you are transferring to will generally give you protection in their scheme. This will not be an underpin as it is unique to the LGPS, instead, you are given a choice between a career average pension and a final salary pension for the relevant pension benefits built up from 1 April 2015 to 31 March 2022.
If you transfer and have a disqualifying break you will lose underpin protection.
Criminals are known to target pension savings so please make sure you read NILGOSC’s pension scam pages before deciding to transfer. https://nilgosc.org.uk/members/leaving/be-fraud-aware/protecting-your-pension-from-scammers/
If you were protected by the underpin and have already transferred your pension out, then NILGOSC will review the transfer value paid and will contact you if an additional payment is due. NILGOSC has over 50,000 records to review so it will take some time before these cases will be reviewed.
For most members the pension that they built up in the career average scheme will have been higher than what would have been built up had the final salary scheme continued, therefore the career average transfer value paid will have been higher than any final salary transfer amount for the period from 1 April 2015 to 31 March 2022 and no payment will be due.