UTM corrupts the qcow2 image when using snapshots too much

[fwrs]

Describe the issue
When you frequently suspend a VM and then restore it, the qcow2 file appears to become corrupted and the vm can't be opened, the qemu-img util can't do anything with it either (like deleting any snapshots)

Configuration

• UTM Version 3.0.4 (46)
• OS 12.2.1 (21D62)
• Apple M1 Pro

Crash log

Not a crash.

Debug log

Running:  -L /Applications/UTM.app/Contents/Resources/qemu -S -qmp tcp:127.0.0.1:4000,server,nowait -nodefaults -vga none -spice "unix=on,addr=/Users/ilyakulinkovich/Library/Group Containers/WDNLXAD4W8.com.utmapp.UTM/ACCFE744-2308-48A7-A8E9-9B7F3F089691.spice,disable-ticketing=on,image-compression=off,playback-compression=off,streaming-video=off,gl=off" -device virtio-vga -device virtio-rng-pci -smp cpus=4,sockets=1,cores=4,threads=1 -machine pc-q35-2.10,vmport=off -accel tcg,thread=multi,tb-size=1024 -global PIIX4_PM.disable_s3=1 -global ICH9-LPC.disable_s3=1 -boot menu=on -m 4096 -device AC97 -name "Windows 7" -usb -device usb-tablet,bus=usb-bus.0 -device ich9-usb-ehci1,id=usb-controller-0 -device ich9-usb-uhci1,masterbus=usb-controller-0.0,firstport=0,multifunction=on -device ich9-usb-uhci2,masterbus=usb-controller-0.0,firstport=2,multifunction=on -device ich9-usb-uhci3,masterbus=usb-controller-0.0,firstport=4,multifunction=on -chardev spicevmc,name=usbredir,id=usbredirchardev0 -device usb-redir,chardev=usbredirchardev0,id=usbredirdev0,bus=usb-controller-0.0 -chardev spicevmc,name=usbredir,id=usbredirchardev1 -device usb-redir,chardev=usbredirchardev1,id=usbredirdev1,bus=usb-controller-0.0 -chardev spicevmc,name=usbredir,id=usbredirchardev2 -device usb-redir,chardev=usbredirchardev2,id=usbredirdev2,bus=usb-controller-0.0 -device ide-hd,bus=ide.0,drive=drive0,bootindex=0 -drive "if=none,media=disk,id=drive0,file=/Users/ilyakulinkovich/Library/Containers/com.utmapp.UTM/Data/Documents/Windows 7.utm/Images/data.qcow2,cache=writethrough" -device rtl8139,mac=DE:F6:CC:2F:28:42,netdev=net0 -netdev vmnet-macos,mode=shared,id=net0 -device virtio-serial -device virtserialport,chardev=vdagent,name=com.redhat.spice.0 -chardev spicevmc,id=vdagent,debug=0,name=vdagent -device virtserialport,chardev=charchannel1,id=channel1,name=org.spice-space.webdav.0 -chardev spiceport,name=org.spice-space.webdav.0,id=charchannel1 -uuid ACCFE744-2308-48A7-A8E9-9B7F3F089691 -rtc base=localtime
qemu-x86_64-softmmu: -drive if=none,media=disk,id=drive0,file=/Users/ilyakulinkovich/Library/Containers/com.utmapp.UTM/Data/Documents/Windows 7.utm/Images/data.qcow2,cache=writethrough: Reference count table too large

Upload VM

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>ConfigurationVersion</key>
	<integer>2</integer>
	<key>Debug</key>
	<dict>
		<key>DebugLog</key>
		<true/>
	</dict>
	<key>Display</key>
	<dict>
		<key>ConsoleFont</key>
		<string>Menlo</string>
		<key>ConsoleFontSize</key>
		<integer>12</integer>
		<key>ConsoleOnly</key>
		<false/>
		<key>ConsoleTheme</key>
		<string>Default</string>
		<key>DisplayCard</key>
		<string>virtio-vga</string>
		<key>DisplayDownscaler</key>
		<string>nearest</string>
		<key>DisplayRetina</key>
		<true/>
		<key>DisplayUpscaler</key>
		<string>nearest</string>
	</dict>
	<key>Drives</key>
	<array>
		<dict>
			<key>DriveName</key>
			<string>drive0</string>
			<key>ImagePath</key>
			<string>data.qcow2</string>
			<key>ImageType</key>
			<string>disk</string>
			<key>InterfaceType</key>
			<string>ide</string>
		</dict>
		<dict>
			<key>DriveName</key>
			<string>drive8B001E31-23AD-47C3-A388-9256BAEAC93A</string>
			<key>ImagePath</key>
			<string>efi_vars.fd</string>
			<key>ImageType</key>
			<string>none</string>
			<key>InterfaceType</key>
			<string></string>
		</dict>
	</array>
	<key>Info</key>
	<dict>
		<key>Icon</key>
		<string>windows</string>
	</dict>
	<key>Input</key>
	<dict>
		<key>InputLegacy</key>
		<false/>
	</dict>
	<key>Networking</key>
	<dict>
		<key>NetworkCard</key>
		<string>rtl8139</string>
		<key>NetworkCardMAC</key>
		<string>DE:F6:CC:2F:28:42</string>
		<key>NetworkMode</key>
		<string>shared</string>
	</dict>
	<key>Printing</key>
	<dict/>
	<key>Sharing</key>
	<dict>
		<key>ClipboardSharing</key>
		<true/>
		<key>DirectoryReadOnly</key>
		<true/>
		<key>DirectorySharing</key>
		<true/>
		<key>UsbRedirectMax</key>
		<integer>3</integer>
	</dict>
	<key>Sound</key>
	<dict>
		<key>SoundCard</key>
		<string>AC97</string>
		<key>SoundEnabled</key>
		<true/>
	</dict>
	<key>System</key>
	<dict>
		<key>Architecture</key>
		<string>x86_64</string>
		<key>BootDevice</key>
		<string></string>
		<key>BootUefi</key>
		<false/>
		<key>CPU</key>
		<string>default</string>
		<key>CPUCount</key>
		<integer>4</integer>
		<key>ForceMulticore</key>
		<true/>
		<key>MachineProperties</key>
		<string>vmport=off</string>
		<key>Memory</key>
		<integer>4096</integer>
		<key>RngEnabled</key>
		<true/>
		<key>SystemUUID</key>
		<string>ACCFE744-2308-48A7-A8E9-9B7F3F089691</string>
		<key>Target</key>
		<string>pc-q35-2.10</string>
		<key>UseHypervisor</key>
		<false/>
	</dict>
</dict>
</plist>

[adespoton]

I can verify I've also experienced this, clicking suspend/restore/suspend/restore rapidly.