Landlords have reacted with dismay to a further rent holiday for struggling businesses, saying it will hit pension schemes, savings, and lenders.
The government extended the protection, which includes a moratorium on commercial evictions, on Wednesday.
Business groups said the support, first introduced in April due to coronavirus, "will provide a respite" for firms.
But landlords said the scheme is being "exploited" by big companies "to preserve cash flow".
In April the government announced a moratorium on evictions for non-payment of rent, which was then extended until 30 September.
On Wednesday the government extended the scheme again until the end of 2020.
Housing Secretary Robert Jenrick said the measures would "stop businesses going under and protect jobs over the coming months."
The government reiterated that the scheme should only be used by businesses who needed it.
The move was welcomed by many retailers and restaurants businesses, which have been hit hard by a decline in footfall.
Deliveroo boss Will Shu said the extension was "hugely welcome news for the sector and our restaurant partners."
"The sector still faces huge challenges but removing the immediate threat of eviction will save thousands of restaurants from bankruptcy," he said.
The British Retail Consortium (BRC) said it is "a difficult time for store-based retailers, who face high costs from coronavirus safety measures, and significantly lower footfall."
Tom Ironside, director of business and regulation at the BRC, said: "While the extension of the moratorium will provide a respite for many struggling retailers, a large Christmas Day rent bill would be a disaster during the all-important peak trading period."
However, the British Property Federation said the extension was "hugely disappointing", adding that "well-capitalised businesses continue to exploit the intervention, refusing to pay rent despite being able to afford it."
Melanie Leech, the chief executive of the body, added that it is "imperative, for the health of the pensions and savings funds that own our High Street, that the government confirms this is the last extension."
The scale of pensions schemes investment in commercial property is "enormous", according to Bruce Dear, head of London real estate at law firm Eversheds Sutherland.
He said pension schemes typically invest between 10% and 12% of their funds in commercial property. Savers also invest in property through Individual Savings Accounts (ISAs).
Some estimates point to about £45bn of UK savings and pensions depending on commercial rent being collected.
Mr Dear said people have a "quasi-feudal" view of landlords "as being incredibly rich landowners who have nothing to do with people... but the majority of landlords in this country are you and me, through our savings and our pensions."
"The dance between landlords and tenants drives the UK economy and it doesn't work if one side has its feet chained together. The government should bring in counter balancing rent support for landlords," he added.
Industry body Revo, which represents commercial landlords, said that the shortfall in rents for the second quarter alone was £1.5bn, and that can "be expected to increase sharply later this month."
"This sudden loss of income will reverberate through the financial system to savers and pensioners that directly or indirectly rely on commercial property for income... The current situation is simply not sustainable," said Vivienne King, chief executive of Revo.
The body added that landlords could start to have difficulty paying their mortgages, which in turn would hit banks, who may then be less willing to lend.
The loss of rental income "may begin to have material impacts on credit supply, if lenders find themselves overwhelmed by defaulting landlord borrowers," Ms King said.