In internet parlance, an “echo chamber” is a sociological phenomenon produced by the algorithms on major websites that respond to our choices of viewing material with suggestions for other options.
Because web designers want users to ingest their content, read their advertising and buy the stuff they are flogging, anything we look at regularly online generates multiple opportunities to do more of the same and fewer and fewer invitations to do anything different. Amazon does it. Google does it. YouTube does it. Your favorite news website probably does it. Everybody does it.
Sometimes it’s merely irritating. Sometimes it’s downright funny. But you must have noticed it.