This is due to the Requester pays policy on AWS S3 bucket for Sentinel data.

See

To all AWS Public Datasets users of S2 L1C data. This thread will be used to communicate changes happening to the S2 bucket. As we expect to gather some feedback from power users in this thread, we might change the approach a bit during the discussion in ongoing. The summarized and harmonized description will be available on this FAQ link.
End of June we will set S2 L1C bucket as “Requester pays” similarly as it is for S2 L2A and S1 GRD. This move is required to allow further increase of the sh…

Thanx for answer!

I’m just an engineer for electronics at the University of Svalbard (UNIS) and not a satellite picture expert. I try to supply our scientist and students with fresh sea ice information around Spitsbergen. Not an amateur but no expert here. I just get nothing out of you answer. What I need are the “tif” files for the B8 channel for Sentinel 2 as an http URL …

There is no such resource available to simply access Sentinel-2 B08 “tiff” file over HTTP.

You could try Sentinel Hub services, which give you exactly that - you ask for a GeoTIff of B08 over a specific AOI and you get it. The services are payable but there are ways to get free accounts for research.