NCBI appeared at least in part to shift onto Google Cloud buckets, one previous OP raised a question about access via GCP (I think the question was closed). Fundamentally, traditional FTP is not sustainable against data growtch. GCP is accessed via gsutil. It would be good if you could contact NCBI and post their official response here. They will response when their database provision is in a state of flux.

sratoolkit appears to be a front-end to GCPs gsutil. Just to point out, it would be very unusual for NCBI to charge the user for e.g. direct gsutil download, because usually the provider will charge e.g. NCBI on a per download basis. This will likely work out cheaper overall for NCBI.

Just to formalise my bit, if SRA are hosting on a GCP bucket, Google will not permit ftp access which is at least part the reason behind your question. 

They do have their own ftp equivalent called `gsutil` which will permit direct download if you know the bucket name. `gsutil` is part of the ClouD SDK package and can be downloaded via conda/anaconda `conda install gcloud-sdk`. This will give you command line access if you know the bucket names. There is a past post on this BTW.