https://github.com/minio/minio/issues/11172#event-4150671037 - Essentially the anwser I got was pretty much tough it’s not going to be fixed, Backblaze said they don’t support ETAG so it’s not going anywhere soon.
I stopped using minio/seafile and went back to nextcloud connecting to B2 directly, it’s a shame but seafile didn’t seem to want to talk to B2 directly and whilst I prefer it to nextcloud at least with nextcloud the files are stored directly on B2 so if the integration breaks I can still get them directly off the backend (I don’t bother with NC’s encryption)