Can't boot to macOS anymore after resizizing macOS partition After installing Ubuntu as a second system on my Macbook following this tutorial https://www.maketecheasier.com/install-dual-boot-ubuntu-mac/ everything was just working fine and I was able to boot into either macOS or Ubuntu via rEFInd.
Then I resized macOS's partition again to create a partition to share data between macOS and Ubuntu. Unfortunately rEFInd does not find the macOS Partition anymore and I am therefore not able to boot into macOS.
My partitions look like this at the moment:
sda             489,1G                              
├─sda1 vfat       200M /boot/efi                    EFI
├─sda2 apfs       351G                              
├─sda3 swap       3,7G [SWAP]                       
├─sda4 ext4     115,5G /                            
└─sda5 vfat      18,6G                              SHARE

Any help would be highly appreciated.
Edits:

I used the builtin Mac Program to resize the partition

Output of sudo gdisk -l /dev/sda:
 GPT fdisk (gdisk) version 1.0.5

 Partition table scan:
   MBR: hybrid
   BSD: not present
   APM: not present
   GPT: present

 Found valid GPT with hybrid MBR; using GPT.
 Disk /dev/sda: 1025610768 sectors, 489.0 GiB
 Model: Crucial_CT525MX3
 Sector size (logical/physical): 512/512 bytes
 Disk identifier (GUID): 2AA86904-096B-4D1C-9DD0-3C8B1FD84B37
 Partition table holds up to 128 entries
 Main partition table begins at sector 2 and ends at sector 33
 First usable sector is 34, last usable sector is 1025610734
 Partitions will be aligned on 8-sector boundaries
 Total free space is 1653 sectors (826.5 KiB)

 Number  Start (sector)    End (sector)  Size       Code  Name
    1              40          409639   200.0 MiB   EF00  EFI System Partition
    2          409640       736548223   351.0 GiB   FFFF  tichan
    3       775612416       783423487   3.7 GiB     8200  
    4       783423488      1025609727   115.5 GiB   8300  
    5       736548864       775612415   18.6 GiB    0700
The type GUID for partition 2 of /dev/sda is wrong. The commands below will correct the problem. Enter the commands in an Ubuntu terminal window.
sudo gdisk /dev/sda
t
2
AF0A
w
y


Note: I realize the gdisk output shows hybrid partitioning. However, both macOS and Ubuntu should ignore the 2nd, 3rd and 4th entries in the MBR partition table.