Logic app bad character

Hi, I created a logic app which gets the data from restapi. The content type of data is Application/protobuf(protobuf is a binary data made by google https://developers.google.com/protocol-buffers/docs/tutorials) I know that LA uses base64 encoding so it changes the data to base64 encoding. As the data to be deserialised via protoc complier so it needed binary format. So i store this data into a variable and trying to paas this further processing. But unfortunately the data stores in variable changes into boxes and ? So protoc compiler fails to deserialised the same.
I tried base64tobinary and http() as per suggestion mentioned section "other content type" on microsoft https://docs.microsoft.com/en-us/azure/logic-apps/logic-apps-content-type#applicationxml-and-applicationoctet-stream
But it did not work. Can anybody help on this?