Attempting to do business deals during the COP process appears to be a serious breach of the standards of conduct expected of a COP president.
Those standards are set by the UN body responsible for the climate negotiations, the United Nations Framework Convention on Climate Change (UNFCCC).
The UNFCCC says the "cardinal principle" for COP presidents and their teams is "the obligation of impartiality".
It told the BBC that COP presidents are "expected to act without bias, prejudice, favouritism, caprice, self-interest, preference or deference, strictly based on sound, independent and fair judgement".
"They are also expected to ensure that personal views and convictions do not compromise or appear to compromise their role and functions as a UNFCCC officer," it continued.
Manuel Pulgar-Vidal, the head of the COP20 summit in Peru in 2014, worries a collapse in trust could mean no progress on tackling climate change in Dubai.
"The president of the COP is the leader of the world, is trying to build consensus on behalf of the planet," he told the BBC.
"If any president of the COP tries to bring a particular interest, [including] commercial interest, that could mean the failure of the COP."
At a press conference last month, COP28 director-general Majid al-Suwaidi said the UAE's climate summit team was "fully independent" of both Adnoc and Masdar.
COP28 has been "very clear about our independence" in discussions with the UNFCCC, he added.
In a statement, the COP28 team told the BBC: "The fact that Dr Sultan al-Jaber holds a number of positions alongside his role as COP28 president-designate is public knowledge and something we have been transparent about from the outset.
"Dr Sultan al-Jaber is singularly focused on the business of COP and delivering ambitious and transformational climate outcomes at COP28," the statement said, adding it would be a "distraction" to suggest that the work he has undertaken has not "been focused on meaningful climate action".
These are serious allegations but ultimately the success of the UAE's leadership of the climate talks, and of the COP28 president himself, will be judged by the results achieved at the summit, experts say.
The COP28 summit is due to end on Tuesday 12 December.
Additional reporting by Adam Eley and Sophie Woodcock