I think the fox they are saying is Taeyeon from SNSD, she is often called like that@cadiz in the comments under the link you posted about Serr1 revealing inside info about dating scandals,there is a comment about chinese sasaeng giving coded hints about bt5 members.It seems that sasaeng permanently deleted her account after posting that.
https://www.allkpop.com/article/2019/08/former-dal-shabet-member-serri-spills-the-tea-on-idols-with-two-girlfriends-dispatch-deals-and-more
The comment:
" Dispatch must know who are dating now, but there are also some Chinese sasaeng that have an interesting information. Guys, remember, many months ago a Chinese sasaeng wrote that a couple of famous Korean actors would divorce, said the actress is older than him, -// detailed the reasons //-, nobody believed her so she deleted everything, then a few months went by and the songsong couple divorce happened, well, then a few months ago that chinese sasaeng wrote again before completely closing her account, she wrote about the most famous kpop group with 7-star, she commented that some members are really in love, the member "E" is so in love with a successful great legend "A" of one of the biggest kpop companies, she is older than him but she never age, he did many things to conquer her love and apparently finally he earned her love, she didn't want to accept his love because of the age difference and to avoid fanwars, he has been in love with her for many years ago apparently he was her loyal fanboy, sasaeng called them (E + A) the most wonderful couple with the most wonderful story of love -// she gave more details //-, another member is "G" who is so in love with a successful Kpop singer soloist "J ", he even tries to surround himself with all the people around her, apparently they are finally getting close, his personality is influencing her personality lately, -// gave more details //-, She also commented that an member "M" who is in love with an almost famous foreign star, but that she only wants him as her friend, he is not her type yet.-// gave more details //- sasaeng also commented that there is a famous korean female legend "F" who pretends to be their friend but that "F" is really a fox who is trying to date any of them (7 stars) to achieve fame and popularity again, she was dating a member of another famous kpop boy group but they broke up, she is not a good person, "F" is a seeker and fake person. chinese sasaeng advises them being careful to give her too much confidence and friendship. -// gave more details // she wrote a lot, but some fans only translated it because that same day she deleted everything and canceled her account."
And this is one of the guesses underneath that comment.
"Abt the coding that this type of sasaeng is using and also the data/info reminds me of an j-sasaeng so I will try to decipher it, it seems she used for male the last letter of his name or nickname.
E is tae-hyung → t a 'E'
G is jung-kook → j u n 'G'
M is r-m → r 'M'
Abt female this is a bit confusing but checking the information + names, I think they are:
A is yoona → y o o n 'A'
J is jieun → 'J' i e u n (iu)
* F, that is just 'F' o x *"
That foreign famous star could be h@lsey.
I don't know if there is any truth in it.And at this point,it looks more like fiction from what has happened all this while.
What are your opinions,guys?
But all sonds like rumors or fanfic....I guess time will tell