Make a flat buffer using terra::buffer

Question

Is it possible to make a "flat" buffer around lines in the same way as st_buffer work:

buf_sf <- st_buffer(st_as_sf(py2),dist = py2$width, endCapStyle = 'FLAT')

for terra it works with round buffers, but I cannot find information on flat buffers:

terra_buffer <- py2|>
  vect() |>
  buffer(width = py2$width, SomeWayToMakeItFlat? = "T")
  st_as_sf()

Make a flat buffer using simple features st_buffer