The administrative team recommended total refusal of the modifications ahead of the official vote by elected councillors.
"The proposal would result in a failure to mitigate the impacts of the development," planning officials wrote.
The financial requirements grew from an original 2016 sum of £102,591 for schools and £16,354 for public spaces to the current total due to inflation and non-payment penalties.
"The concern with this one is that most of the site is completed with the last seven plots and road to be adopted the last things to sort," said Councillor Chris Emmas-Williams, Labour leader.
The council leader expressed frustration with the recurring industry practice of developers seeking retrospectively to alter signed infrastructure agreements.
"I have a lot of sympathy for the residents but with the county council saying the funding was still needed, our hands are tied," said Councillor Chris Emmas-Williams, Labour leader.
The developer had previously raised concerns about completing the final remaining plots and roads if forced to pay the full infrastructure bills.
"I do get annoyed when developers have applications approved with Section 106 to cover for improvements and the inconvenience of the development and then they come back and say it is no longer viable," said Councillor Chris Emmas-Williams, Labour leader.
The local authority has raised the issue with the national government to ensure future compliance with initial planning permissions.
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"I have said to the Government that I don't think this is the right way to do things and that developers should adhere to what they agreed to," said Councillor Chris Emmas-Williams, Labour leader.
