Have same issue - installer woeks fine, but both gtk and qt versions just show gray screen for a brief moment and close. Uninstalling and reinstalling does not help. Nothing meaningful in the console:
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2023/07/06 14:04:29 itch-setup will log to /tmp/itch-setup-log.txt
2023/07/06 14:04:29 =========================================
2023/07/06 14:04:29 itch-setup "v1.26.0, built on Apr 22 2021 @ 04:48:12, ref 48f97b3e7b0b065a2478811b8d0ebcae414845fd" starting up at "2023-07-06 14:04:29.305576021 +0300 EEST m=+0.004743940" with arguments:
2023/07/06 14:04:29 "/home/dino/.itch/itch-setup"
2023/07/06 14:04:29 "--prefer-launch"
2023/07/06 14:04:29 "--appname"
2023/07/06 14:04:29 "itch"
2023/07/06 14:04:29 "--"
2023/07/06 14:04:29 =========================================
2023/07/06 14:04:29 App name specified on command-line: itch
2023/07/06 14:04:29 Locale: bg-BG
2023/07/06 14:04:29 Initializing installer GUI...
2023/07/06 14:04:29 Using GTK UI
2023/07/06 14:04:29 Initializing (itch) multiverse @ (/home/dino/.itch)
2023/07/06 14:04:29 (/home/dino/.itch)(current = "25.6.2", ready = "")
2023/07/06 14:04:29 Launch preferred, attempting...
2023/07/06 14:04:29 Launching (25.6.2) from (/home/dino/.itch/app-25.6.2)
2023/07/06 14:04:29 Kernel should support SUID sandboxing, leaving it enabled
2023/07/06 14:04:29 App launched, getting out of the way
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however dmesg shows this:
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[794401.060522] traps: Chrome_IOThread[230758] trap int3 ip:55e52ca12649 sp:7fe4771f84e0 error:0 in itch[55e52a3af000+6068000]
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Using Debian 12 on twin Opteron 6378, NVidia GTX 970 with non-free drivers