ResidentMario:

        x = self.dequant_1(x)
        x = self.conv_1_4(x)



If the intent is to dequantize and want to do conv_1_4 in fp32, then the problem is that by default, the quantization APIs quantize all convolutions in the model.  The workaround would be to disable quantization for conv_1_4, like this:
model.qconfig = ...
# disable quant for a specific layer
model.conv_1_4.qconfig = None
# continue with the quantization APIs, conv_1_4 will not be quantized