Maybe Syphrus just was hiding documents in the notebook because it looked inconspicuous. Rather than just have them in the open. https://www.amazon.com/Fingerprint-Encrypted-Notebook-Charging-Journaling/dp/B07WD3WHGX

Here is the link to the exact same journal yall found ,someone may already done this but who knows maybe you can find something about it https://www.amazon.com/Fingerprint-Encrypted-Notebook-Charging-Journaling/dp/B07WD3WHGX

Notebook Theories/Discovery

Ok so I think the note book is a smart reusable one like this https://getrocketbook.com.au/products/rocketbook-wave

The only thing going against this theroy is there was no qr codes or anything you would scan to digitise your notes.

My next thought was maybe the information was being stored via the USB port but after some research and finding this https://www.amazon.com/Fingerprint-Encrypted-Notebook-Charging-Journaling/dp/B07WD3WHGX

The USB port is to charge the battery which I assume is for the finger print scanner.

This is when I made this discovery, the battery in that notebook has a standby time of 6 months...

The fact that it still turns on tells you that that notebook has been in that car a little under 6 months! So any time between now and say May of this year!!

Discovery

I found the journal on Amazon. I know we don't need it anymore but thought I'd still share it.

https://www.amazon.com/dp/B07WD3WHGX/

....and HERE is where I asking some questions......first of all...the journal you find have only 180 days of battery (checked that up. "https://www.amazon.com/Fingerprint-Encrypted-Notebook-Charging-Journaling/dp/B07WD3WHGX") and if you didn't have a charger for this journal there is this other questions: 2. How can the journal still have batteries after al this YEARS (not only 180 DAYS....)? 3. If the guy knew about the car...about the safe with keys...about the safe with the chemicals......and even know where the rooms are.....HOW come he didn't smashed the BACK door window and ripped up the seat from outside? He didn't even had to open the door........so much things that feels a little bit hmm...fake?....like hollywood-fake whit cameras...evidence...no cops (you say that you called them...and you THINK they don't show up because you are youtubers......but you are still tax-payers and humans!)...just sayin'

The Journal

Alright so i have been doing some research on that Journal and i think i found it. Here is the link to what i think the Journal is:https://www.amazon.com/Fingerprint-Encrypted-Notebook-Charging-Journaling/dp/B07WD3WHGX. hopefully this can help someone with another discover. (P.S. Definitely take a black light to it just in case)

It could be invisibale ink

so I looked for this journal and I found it on amazon and it says that the battery could last for 6 months so the journal should have been put into the seat for at most 6 months, so it's after you purchased the laboratory unit

https://www.amazon.com/Fingerprint-Encrypted-Notebook-Charging-Journaling/dp/B07WD3WHGX

also, the journal could have writing on it with invisible ink and almost every invisible ink uses UV light so try to shine a UV light on it and see if there is anything, also in the past, they used some kind of invisible ink the would only show if it's heated so try that also

Journal in the seat

I found the journal on Amazon and thought that you would like to see it.

https://www.amazon.com/Fingerprint-Encrypted-Notebook-Charging-Journaling/dp/B07WD3WHGX

The diarys battery lasts about half a year, as it says. So some one had to hid/charge the diary less than half a year ago, since it still had power, so it happened after we found the first keys, and before returning of the key series...

I could find the diary on Amazon, but the one we found must have been custom made, because of the Syphus logo

Link: https://www.amazon.com/Fingerprint-Encrypted-Notebook-Charging-Journaling/dp/B07WD3WHGX#customerReviews