I forgot the title, but I remember it was a short-lived manga series. It was a bit similar to the Jim Carrey movie called "Truman Show"

At the start of the series, a schoolgirl finds out that her activities and habits have been recorded in a manga. She gets embarassed especially by the shower scene and attempts to avoid the situation throughout several chapters. Then she discovers that the world is disappearing and most of the characters are becoming faceless. At the school, she finally found two classmates who didn't disappear. The male classmate theorized that they are living in a manga and their world is not real. The schoolgirl responded in disbelief. But the male classmate said he could not remember anything before this. The female classsmate concurred.

On the train, she privately compares it to the Truman Show in her thoughts.

When the schoolgirl came home, she saw her family are faceless, too.

I tried looking for it on the net but the description was too generic so I found no satisfying results.

𝗛𝗲𝗿 𝗟𝗶𝗳𝗲 𝗜𝘀 𝗖𝗼𝗺𝗶𝗰𝗮𝗹𝗶𝘇𝗲𝗱
(Jibun No Koto Ga Katte Ni Manga Ni Sareteru Onnanoko).

ᴡᴀᴛᴄʜ ᴛʜᴇ ꜱᴜɴʀɪꜱᴇ ᴀʟᴏɴɢ ᴛʜᴇ ᴄᴏᴀꜱᴛ,
ᴀꜱ ᴡᴇ'ʀᴇ ʙᴏᴛʜ ɢᴇᴛᴛɪɴɢ ᴏʟᴅ,
ɪ ᴄᴀɴ'ᴛ ᴅᴇꜱᴄʀɪʙᴇ ᴡʜᴀᴛ ɪ'ᴍ ꜰᴇᴇʟɪɴɢ,
ᴀɴᴅ ᴀʟʟ ɪ ᴋɴᴏᴡ ɪꜱ ᴡᴇ'ʀᴇ ɢᴏɪɴɢ ʜᴏᴍᴇ.

𝖽4𝗏𝖽 - 𝖧𝖾𝗋𝖾 𝖶𝗂𝗍𝗁 𝖬𝖾
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OMG. Oh yes! That is the title I was looking for. Thank you very much.

𝗛𝗲𝗿 𝗟𝗶𝗳𝗲 𝗜𝘀 𝗖𝗼𝗺𝗶𝗰𝗮𝗹𝗶𝘇𝗲𝗱. Yes that is it.