This session close reason is also used for receiving response
bodies, for example:

--  TTL            RFC 86400 10 0 1652368707 1652368707 1652368707 0 86400 cacheable
--  VCL_call       BACKEND_RESPONSE
--  VCL_return     deliver
--  Timestamp      Process: 1652368707.157422 0.063369 0.000054
--  Filters
--  Storage        file s0
--  Fetch_Body     2 chunked stream
--  FetchError     chunked read err
--  BackendClose   53 self close Failure receiving req.body
--  BereqAcct      1337 0 1337 987 3465216 3466203
--  End