There are no such plans. There is an established precedent across multiple administrations that former Ministers may be supported with legal representation after they have left office when matters relate to their time and conduct as a Minister. The Public Duty Cost Allowance exists for a different purpose.
I refer the Noble Lord to the transcript of the Public Administration and Constitutional Affairs Committee meeting on 26 January 2023, where Alex Chisholm, the Permanent Secretary of the Cabinet Office, provided oral evidence on this matter: https://committees.parliament.uk/oralevidence/12604/pdf/ (Q299-315).
PACAC Transcript (26.01.23) (pdf, 281.3KB)