Can I as a Bloodhunter create mutagens without doing a short or long rest?

As a 2020 version of the Bloodhunter/mutagen order, at lvl 3 I can create one mutagens in a short/long rest.

I read this handbook:

As a possible fix: Instead of preparing your mutagens during a rest, you prepare reagents for mutagens.

Creating a mutagen requires one minute of uninterrupted work with these reagents and a set of alchemist’s tools. This allows the Blood Hunter a bit more flexibility with their mutagens, but not so much that they can change them during combat."

I don´t really understand where he gets that with the reagents. I can´t find it in the books and nothing about it on the internet.

This way I could do a 1 min pause and prepare the mutagen without doing a short rest.

I hope you can help me to understand it better.