Thank you. Also many thanks to @openminded who gave a very simple and quick explanation of the meaning of all this.
About grub.pacnew files… I have read the wiki on System Maintenance, but I’m having trouble understanding. I have an original (I suppose old) grub file edited to my preferences. And everytime there was a grub update, I would get a grub.pacnew file, which I suppose was the updated version of grub. I have never attempted to merge or overwrite my original grub file with the grub.pacnew file before. Currently my system (dual-boot installation with Windows which I never use, only have it as a backup plan) runs with the original grub file and therefore the os-prober is enabled by default (and lots of other lines that exist in the .pacnew file are missing from the original grub file).
Can you please explain to me if I have to completely ovewrite the original file with the .pacnew and then re-edit in my preferences? What risks are involved in doing so (is there a risk of being unable to boot into manjaro) and what happens if I never handle the .pacnew file and let my old grub file as is? Is there a safe or recommended way of handling this?
EDIT: I found a topic that answers my questions aptly enough, for anyone else out there who is inexperienced about .pacnew file maintenance. Timeshift is up and running, copied the current grub file as a backup on a separate partition, doing a back-up of my personal data just in case (nobody can really afford to lose working hours) and then I am going to tackle the handling of grub.pacnew with DIFFPROG=meld pacdiff, while being aware about the latest changes in grub configuration (os-prober). I honestly had a lot of trouble trying to understand what I need to do and which command to use exactly, but things are getting clearer now.
I apologize if I went off on a tangent here.