I see it similarly to how you wrote it, but doesn’t it say exactly there that until 1.7.2021 KfW applications can be submitted as usual (old conditions)?
I think this statement from the BMWi comes closest:
"Can I switch to the loan option if I have applied for an individual measures grant from BAFA and vice versa?
A direct switch in the type of funding for a measure within the ongoing procedure is not possible.
However, if you have not yet started the measure and meet the application requirements for loan funding through the EBS program 152, you can submit a new application via your house bank to KfW under program 152 upon waiver of the BAFA grant."
The same then applies analogously for programs 151 and 153 (new construction).
and here the other statement
"What if I planned individual measures (with BAFA grant approval) and then decide to perform a full renovation to an efficiency house – can I switch, what is the project start?
A new application to the KfW for efficiency house funding is only possible if all application requirements for the EBS program 151 are met, especially the timely submission of the application before the project start. Currently, the start of construction work is considered the project start in these EBS programs."
If this is interpreted analogously for new construction (instead of full renovation), the same applies here: as long as the start has not yet occurred, I can switch from the individual measures (BAFA) previously applied for to KfW. I no longer see BAFA funding and the KFW program being used simultaneously from 01.01.2021.
I assume that the state now wants to eliminate this hidden double funding of BAFA and KfW. This was previously only achievable via detours. The KfW loan was not allowed to be used for heating technology.
PS: Of course, I think if you now still apply for BAFA funding and then next year apply for construction financing through the bank and include the KFW component, both can still be used, as it would probably only be noticed at the earliest when merging into the BEG. However, this would likely be considered subsidy fraud according to the current state of knowledge. I hope this will be clearly clarified again in December through the information sheets.