Interesting. That is a common trend I have noticed - there is some class of dev whose job becomes serving the internal business on an adhoc basis

your manager can either stop it by charging your time back to the requestor ( I would suggest you track the requests -send emails sayi g Bob you wanted a new sales report, it's third on list and expect it 9am)

or he can explicitly Market you to the business - what I previously did. And it is a powerful weapon for your manager. The higher ups feel well treated and the department gets all it's interrupts funnelled thru one person, who in your case seems good at it and happy to do it

but I strongly suggest you track the work, and push the marketing value of what you do.