Reduction in relief for AIM

Hi all,
I've been asked to respond to a client as to why specifically AIM has had a reduction in IHT relief from next year. I can't seem to find anything and I must have lost Rachel Reeves' phone number... Can anyone shed any light?
Thanks
Comments
"The rate of relief will reduce from 100% to 50% in all circumstances for shares traded on but not listed on the markets of recognised stock exchanges (see HMRC’s list of designated recognised stock exchanges), such as AIM.
https://www.gov.uk/government/consultations/reforms-to-inheritance-tax-reliefs-consultation-on-property-settled-into-trust/reforms-to-inheritance-tax-agricultural-property-relief-and-business-property-relief-application-in-relation-to-trusts#:~:text=The rate of relief for,study 1 in Annex A).
If the client is why AIM has been targeted, it's because the Government needs to raise revenue and people were using AIM shares to reduce/eliminate their inheritance tax liability.