I think the unspoken part is the new manager do not have the clout to push back users/stakeholders, both due to being new and the team having already lost trust

I think the unspoken part is the new manager do not have the clout to push back users/stakeholders, both due to being new and the team having already lost trust of its users/stakeholders. Adding more people may not be the only option, but pushing back demands or changing the wider organizational dysfunction is probably not even on the table.