Here, edited, are the final lines of your log
2023-05-12 18:47:20,329 INFO [JavaFX Application Thread] e.e.i.c.MainWindowController [null:-1] ResetNextButtonEventHandler()
2023-05-12 18:47:20,667 DEBUG [Thread-20] e.e.i.t.CommandExecutionTask [null:-1] updateParameters(), Parameters = {device_id=6c0623b5, fastboot_folder_path=/snap/easy-installer/32/easy-installer-linux-x64/bin/adb/}
2023-05-12 18:47:20,668 DEBUG [Thread-20] e.e.i.t.CommandExecutionTask [null:-1] getFullCmd(), full command = [/snap/easy-installer/32/easy-installer-linux-x64/bin/scripts/reboot-fastboot.sh, 6c0623b5, /snap/easy-installer/32/easy-installer-linux-x64/bin/adb/]
2023-05-12 18:47:20,947 DEBUG [Thread-15] e.e.i.t.DownloadTask [null:-1] timeoutThread is over!
2023-05-12 18:47:42,289 INFO [JavaFX Application Thread] e.e.i.EasyInstaller [null:-1] stage is closing
I cannot explain this. [2]
As I understand it reboot-fastboot.sh [1] has the simple job of reboot bootloader but this fails to happen be able to move forward.
Perhaps someone more familiar can provide an explanation.
[2] Interesting, compare this thread PC can't find OnePlus 7T driver during bootloader mode