The difference between nn.Conv1d and nn.Conv3d is the expected shape of the input (and thus also the kernel shape etc.).
nn.Conv1d would be used for “temporal” signals in the shape [batch_size, channels, seq_len], while nn.Conv3d is used for “volumetric” signals in the shape [batch_size, channels, depth, height, width].
Based on the comments from your code you are starting with a 5D tensor, which suddenly gets reduced to a 4D one, so I would assume that either the comments are wrong or the model is not working at the moment.