DfE have confirmed that on that Covid counts as an exceptional circumstance under which ratios may be flexed. Guidance will be amended shortly to reflect this:
It remains a priority to continue providing face to face education and childcare, but we know that COVID-19 continues to put early years settings under significant pressure, particularly in relation to workforce absence.
Government considers COVID-19 to be an exceptional circumstance in which the staff-to-child ratios set out in the EYFS can temporarily be changed if necessary, for example to respond to COVID-related workforce absences. This relates to paragraph 3.31 in the EYFS.
In some cases, providers may choose to respond to staff and child absences by temporarily mixing age groups of children who would otherwise be educated or cared for separately. Ratios should be guided by all relevant requirements and by the needs of individual children within the group. For the purposes of meeting EYFS ratio and qualification requirements, all staff educating or caring for a mixed age group of children can be considered ‘available to work directly with’ all the children who have been grouped together.
In all circumstances, settings remain responsible for maintaining the quality of care, safety and security of children.Email from DfE, 10 January 2022