MacOS partition startup Volume and Recovery Disk type FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF plus part of the disk corrupted

I have a situation very similar to the ones depicted in two previous questions I found (this and this), but still different (I address why my situation is different later on in the question).

The problem

I am really panicking, my computer has been in unbootable status for two days now and because of coronavirus lockdown, in Italy there is no any opened tech shop, at this point I do not know what to do and any help is very much appreciated.

I had a ~50 GB linux partition on the SSD (total ~250 GB) of my 15” Macbook Pro mid-2015.
I created this partition to boot ubuntu back in 2016 and I used it regularly alongside macOS.
About one year ago I updated to Mojave 10.14, and this is the macOS version my computer is running now (I am mentioning it because I suppose that the update changed the file system of my macOS partition to APFS, keeping unmodified the ubuntu partition, I guess).

Today I decided to remove the ubuntu partition, I started the computer on macOS, opened Disk Utility, find the ~50 GB partition assigned to ubuntu on the pie chart, I clicked on the “-“ sign to remove the partition and then “Apply”.
Disk Utility returned to me instantly with an error (not remember exactly the text, but I remember that no error code was given) saying it could not perform the operation, so I googled a bit some solutions (MY COMPUTER WAS PERFECTLY WORKING) and I found a post suggesting to perform some operations from ubuntu, so I decided to restart my computer in order to open ubuntu – I repeat, it was perfectly working, many apps opened and fully working, etc. – and…

It booted into “GNU GRUB version 2.02”

I tried to restart my mac keeping “option” pressed, but it could only find the “EFI Boot” disk (picture attached) which is the one I usually select to boot Ubuntu.
Also, Ubuntu now doesn’t even work anymore, because if I select “EFI Boot” it starts “GNU GRUB version 2.02”.

Now I really started panicking, I don’t care about data of the ~50 GB ubuntu partition, but so foolishly I haven’t backed up the ~200 GB macOS data, and I am just so affectionate to them, I would really like to recover them.

Data Recap

• 15” Macbook Pro mid-2015
• Right now I am booting from the network.
• 256 GB SSD partitioned in:
• ~200 GB APFS macOS partition – FileVault encrypted – running Mojave 10.14
• ~50 GB ubuntu partition – don’t remember the file system (data here doesm’t matter to me)

Photos Attached

• diskutil list
• gpt -r show /dev/disk1
• disk1 information from Disk Utility
• Disk Utility overview of the physical disk
• booting situation with only the “EFI Boot” partition

Why my situation is different

My situation is different from other questions because of 3 reasons:

• The ~50 GB ubuntu partition is disappeared, maybe corrupted, indeed if you add up all the disk's size in diskutil list, you still miss ~50 GB.
• I have 2 disks at the same time (index 2 and index 3) that are in the FFFFFFFF-FFFF-FFFF-FFFF-FFFFFFFFFFFF status
• When I call gpt -r show /dev/disk1 I don't get any "Suspicious MBR at sector 0" message unlike others users that wrote other questions.

Update 1

I just wanted to confirm that I am booting the mac from Network Recovery and also my Disk Utility version.
Disk Utility Version is: "Version 13 (606)" – "Copyright 2002-2014 Apple Inc.". Is seems, indeed, pretty old.