I have problems with FF too (+uBlock Origin +DuckDuckGo Privacy). Loading the data from Google seems to fail:
code 403
message Requests from referer https://sheets.googleapis.com/v4/spreadsheets/1A3xz8NFWjebuMbGWvy2yUBKcnAmuZSs5JmKq9-JDss8/values/Email?key=AIzaSyCxiboNdLE5nSch2pdwI3blsfvfyss3Y0M are blocked.
status PERMISSION_DENIED