a poor waif in his underwear 

A pro-Russian journalist or Russian/Kremlin official who attempts to pass off fake quotes as real things said by government or military officials in Western countries but are clearly fake due to translated Russian phrases, strange wording, words being used in strange or unnatural ways, etc.

The phrase comes from an article written by Seymour Kersh, a pro-Russian journalist. In the article, he claimed an anonymous American official called President Zelenskyy of Ukraine 'a poor waif in his underwear'. However, the term 'waif' is extremely uncommon in American English, and the whole phrase was a Russian meme until the publishing of the article.

Seymour Hersh was a poor waif in his underwear when quoting his source, a supposed 'anonymous US official', who used the Russian idiom 'a poor waif in his underwear', which until then was not used in English.

Pro-Kremlin social media users were floundering like poor waifs in their underwear to dismiss the initial use of 'a poor waif in his underwear' as a mere translation issue without explaining why there would be a translation issue between a US journalist and a US official.

a poor waif in his underwear by True Squatch July 28, 2023

a poor waif in his underwear 

a person who has blown their cover as a Kremlin propagandist, especially when it is unclear they even knew they were one

Seymour Hersh was a poor waif in his underwear when quoting his source, a supposed “anonymous US official”, who used the russian idiom “waif in his underwear”, which until then was not used in English.

a poor waif in his underwear by 504jdw July 28, 2023

a poor waif in his underwear 

people who blow their cover as Kremlin propagandists

He called him"a poor waif in his underwear", so he's definitely not a native English speaker

a poor waif in his underwear by saint-G July 28, 2023