Other than 35_deepin_gfxmode, everything seems exactly like the 'standard' manjaro grub.
I don't know what's in that 35_deepin_gfxmode that can override the usual 10_linux. I hope the authors of that (but your grub packages are manjaro's) grub know why they need to have that extra '35_deepin_gfxmode. It is never a good thing to mishmash up grub.d (that's the problem with grub-customizer). Even some distro modifications (of grub) are exasperating (like Fedora's) but at least their mechanism is consistent and we can know what to expect and can handle them.
You can take a look at 35_deepin_gfxmode (and I wonder where this comes from) but at best I can guess (without certainty - I am not a coder) what this tries to do. Maybe you can do better. Hopefully, some manjaro developer working on deepin can tell us.
I don't use deepin though I had tried the original non-distro version when it was new. Have never tried any deepin since.
But off-hand (and I don't like doing this (off-hand thingy), this 35_deepin_gfxmode seems 'wrong', like our 01_menu_auto_hide (not offhand - I tested thoroughly).
So, with this 35_deepin_gfxmode, I cannot say with certainty, what you should do.
If you have a 'pure' manjaro grub, at least I can be more certain.
I can be rash and tell you to remove 35_deepin_gfxmode and do the 'standard way' but I am still not sure if your other things (like 10_linux) are the 'standard' manjaro 10_linux.
That's saying a lot and I can appear too careful but unless I am sure (like shim keys are microsoft keys), I'd rather not take my chance with other people's system.
But tell us if what you do results in. Cheers.