Sorry, but you seem quite uninformed about this topic.
The court documents related to Harry's ridiculous RAVEC case described different 'tiers' of individuals. Tier One was those individuals automatically entitled to full protection regardless of threat assessments. Titles were redacted but we can assume it means people like the PM and the most senior royals.
Tier Two was those individuals who are granted protection on the basis of threat assessments, but this level of protection is subject to review. This was the category Harry belonged to prior to Mexit. We can see it in action with other royals such as Princess Anne or Prince Edward. They were the children and now siblings of Monarchs, but only get protection when on official duty, not as an automatic entitlement.
Since finding freedom, Harry is now in a different category whereby his security needs are monitored and provided he cooperate, all relevant security will be provided. Nobody can tell me just why this is inadequate.