PLEASE HELP : is Margin in recruitment/hiring haram?

I have been working as a recruiter to a company that delivers contractors to work on projects. (not an agency ), and in some of those projects the company I work for does an agreement with the customers to deliver contractors based on charge rate (charge rate is : candidate’s rate + margin (that is between 10%, 15% 20% 25%) )- now I have heard previously that margin is haram, but my understandment is that it’s only haram for things like leverage margin with brokers or in financial solutions or even bank businesses. - and considering I am in recruitment which is a different environment and not taking a percentage out of that profit (except regular standard salary) I would think that it won’t be considered haram, as my role is to source and hire the talent, and when I am sharing the candidate I put the charge rate (that I mentioned above) meaning I do have direct contact to calculation of margin’s rate - and what I want to know is :

1- Is having margin in candidate’s rate considered Haram ?
2- if I am not taking any profit out of it , would it be okay that I am working in a company that is doing margin in recruitment ?
3- if this won’t be harram - in what situation this might become Haram? (so I know if that situation will happen )
4- I am sometimes the one who calculate margin before sharing with the customer, will that change the answer as I am engaged in that process? if I won’t have engagement in that calculation, will it change it being haram for me (if it is Haram )?

I would appreciate having answers on this, and if there are any points that I haven’t included I would love knowing of from people of experience as I can’t find sources on this to recruitment margin (internet mostly only includes situations of margin in financial business and when dealing with banks and when dealing with brokers or sales ) so having feedback on this based on the business I work for would be highly appreciated

Much appreciation for any guidance,