The question, if it even is a question, illustrates a profound lack of understanding of the systems of staff review AND of the circumstances of "purdah."
Purdah: https://commonslibrary.parliament.uk/research-briefings/sn05262/
There is no mention of a local council election in the OP but this might be assumed?
Assuming there IS a local council election purdah does not in any way restrict routine business of local government although there is a recommendation that contentious or sensitive issues might be avoided.
A staff review leading to a potential wholesale redundancy is a significant, long term planning and execution event which (confirmed in the OP) has already received a mandate - albeit a strange and somewhat illogical timeframe when considered against budget planning timelines.
Do you have local council elections 2 May 24?
If yes there may be a purdah period but it is important to understand what that actually means for your council.
It appears 'odd' that such a major decision as 5 staff redundancies (how many total staff are there?) should be implemented so close to an election but only those in the locale will know what the % chance of significant electoral change might be.