Earlier quoted context omitted.
I find this dictionary definition quite fitting: "2. any method of controlled systematic indoctrination, especially one based on repetition or confusion" https://www.dictionary.com/browse/brainwashing
Then you didn't find definition 1 quite fitting.
"a method for systematically changing attitudes or altering beliefs," fits very well. "originated in totalitarian countries" not so much, and "especially through the use of torture, drugs, or psychological-stress techniques" very little, although it's an "especially", so not a required feature.
The "originated in totalitarian countries" is a bit odd requirement for my taste. Of course, if one wants to use that definition, then by definition even "a method for systematically changing attitudes or altering beliefs the use of torture, drugs, or psychological-stress techniques" is not brainwashing if it doesn't originate from a country that is defined as totalitarian with some definition.