Calamares deleted all data on partition

I have choosed to format partition and install there but calamares have moved all files from that partition to another before formatting and have deleted all the files on that another partition. Is it normal ?

Without knowing the exact settings you made, a detailed summary of the final outcome and the install log it is not possible to understand what happened.

Added logs.

2024-04-27 - 19:28:47 [6]:     ..  mapping for "/dev/sdb2" "/dev/sdb2" 
     partlabel :   "" 
     partition-uuid (partuuid) :   "PartUUID$fed8c03" 
     parttype :   "" 
     partattrs :   "0" 
     mountPoint: :   "/" 
     fs: :   "ext4" 
     fsName :   "ext4" 
     filesystem-uuid (uuid) :   "FSUUID$e9e11835" 
     claimed :   "true"
 [PYTHON JOB]: "sdb                                                                                                             931.5G\n" 
[PYTHON JOB]: "|-sdb1     ext4     1.0              Mint       XXXc4                            701.4G\n" 
[PYTHON JOB]: "|-sdb2     ext4     1.0              Arch       XXX91  206.9G     3% /           229.6G\n" 
[PYTHON JOB]: "`-sdb3     vfat     FAT32            EFI        XXXA7                                                         512M\n"

Looks like you do replace Arch on sdb2 eith EndeavourOS? But i see also you do insrall in Bios legacy Mode:

[PYTHON JOB]: "Bootloader: grub (bios)" 
    .. Running QList("grub-install", "--target=i386-pc", "--recheck", "--force", "/dev/sdb")

but i see EFI partition… on a dos scheme drive?

[PYTHON JOB]: "Disk /dev/sdb: 931.51 GiB, 1000204886016 bytes, 1953525168 sectors\n" 
[PYTHON JOB]: "Disk model: TOSHIBA DT01ACA1\n" 
[PYTHON JOB]: "Units: sectors of 1 * 512 = 512 bytes\n" 
[PYTHON JOB]: "Sector size (logical/physical): 512 bytes / 4096 bytes\n" 
[PYTHON JOB]: "I/O size (minimum/optimal): 4096 bytes / 4096 bytes\n" 
[PYTHON JOB]: "Disklabel type: dos\n" 
[PYTHON JOB]: "Disk identifier: 0xab16b348\n" 
[PYTHON JOB]: "\n" 
[PYTHON JOB]: "Device     Boot      Start        End    Sectors   Size Id Type\n" 
[PYTHON JOB]: "/dev/sdb1        481484800 1952475034 1470990235 701.4G 83 Linux\n" 
[PYTHON JOB]: "/dev/sdb2             2048  481484469  481482422 229.6G 83 Linux\n" 
[PYTHON JOB]: "/dev/sdb3  *    1952475136 1953523711    1048576   512M ef EFI (FAT-12/16/32)\n" 

[PYTHON JOB]: “Disklabel type: dos\n”

Would need some more info from your side to see what exactly is the issue…
Calamares will not move files from one partition to anpother… it only does in case resizing of a partition if you choose that option (install aside) it will ask to mark a partition and it will resize it to make space for the OS to install.

In case please give the output of:
sudo fdisk -l | eos-sendlog
From booting into the ISO