[tinkertim]

You have any browser extensions that might be misbehaving? (I work for Stack Exchange). Nothing on our side could be sending that to you.

[alandarev]

Using other stackexchange sites is fine.

I am no longer able to validate whether addon-less browser would work, as the issue is mysteriously resolved now.

[tinkertim]

I blame Cthulhu. Mystery solved.