I've been having some odd internet things happening lately - random blocks on sites with rejected or firewall errors, sites seeing individual requests stripped of credentials so think I'm logged out until I re-navigate manually (which kicks me out of online banking), random instances of my browser saying it doesn't understand the fetched data, google related sites throwing up abnormal traffic detected messages at random asking me to tick the not a robot check and stuff like that - 99% sure it isn't malware on my end and doesn't seem to matter OS, device, connection or browser used.
I thought at first one of the guests I had over maybe had an infected device which was tripping security measures but had occasional instances of similar stuff since they left.
At a guess there is some kind of malfunctioning or compromised hardware somewhere on the backend infrastructure or measures in place to mitigate an attack or something.
EDIT: The error you are seeing is probably another variant of the stripped credentials with the sites not receiving your user-agent string or something like that - smells to me like a malfunctioning system doing traffic inspection/logging/snooping.
