Thanks Grzegorz @Grzesiek2010. You're 100% correct as this feature was an unsaid beauty in recent past.
I think that feature was very helpful. I've explained in this feature request of its benefits and request that it be brought back in some shape or form: Form+Media updates from central even when submission account is Google: Separate Server and Account Settings in Collect
I am really hoping we can re-enable that as ODK Collect is capable of hosting forms from Central that can submit to Google sheets. It's counter-intuitive to block form update flexibility while submissions are allowed. I am open to suggestions of reasons (other than purely technical) because it's a good part of the product portfolio. It's better let the user pick this as a preference in general settings. Either update based on form source or based on General Settings->Server
Appreciate if this can be shared within your team.
We've also done alot of development that relies on this flexibility. Really hope something can be done about it.