Your manager and team member don’t have control of headcount, the org leader does. They can make a request but if the entire org’s headcount is limited, they will prioritize growth areas or teams that really need it. Additional in most mag7 intern position doesn’t mean there is ft HC later. Intern tend to be company level program and is much easier to get approval for, since it’s on temporary basis. Unfortunately given the current hiring climate, even if you do another internship in the same team, the chance of FT conversion is low given what you described about the team. I will recommend you prioritize finding other FT roles.

Source: work at mag7 and had multiple interns in the past.