7 sourced reports, with what to check before you buy. Each one links to the page it was reported on.
Costly or dangerous
APU power limit hard-locks to ~4-7W on wake from sleep (SteamOS 3.8)
Owner report on the Valve SteamOS tracker for the RC71L Z1 Extreme (BIOS 342) that after sleep/wake the APU is stuck at the lowest TDP, making the device effectively unusable until reboot.
What to check. If you run SteamOS/Bazzite on the Z1 Extreme, wake-from-sleep can leave the APU locked at ~4-7W; a reboot is the workaround. Check for a fixed SteamOS build before buying for this use.
ROG Ally microSD card reader malfunctions under thermal stress (ASUS-confirmed)
ASUS itself confirmed the reader can malfunction under thermal stress, with some users' cards permanently damaged.
What to check. Treat the microSD slot as unreliable for long sessions; prefer the internal SSD or a larger 2230 SSD for storage. If a card stops being read, test it in another device before assuming the card is dead.
microSD card reader malfunctions under thermal stress (official ASUS confirmation)
News report quoting an ASUS representative confirming the integrated microSD reader can fail under heat; ASUS shipped a fan-speed update to mitigate, but damaged readers need board-level repair.
What to check. Do not rely on the microSD slot for primary storage on the Z1 Extreme; heat from the exhaust-adjacent reader can kill cards. Keep long sessions off the SD card or accept the risk.
Fatal D3D device-hung crash (DXGI_ERROR_DEVICE_HUNG) during games
Microsoft Q&A thread on a ROG Ally RC71L with the Ryzen Z1 Extreme hitting a fatal D3D device-hung error (0x887a0006) during games under Windows 11.
What to check. Expect occasional graphics-driver crashes on the Z1 Extreme under Windows; the DXGI_ERROR_DEVICE_HUNG error is a known pattern that driver/BIOS updates may or may not fix. Keep GPU drivers current.
MediaTek MT7922 WiFi disconnects and networks disappear until reboot
Owner report on the Bazzite forum that the MT7922 WiFi card drops all networks minutes after boot and requires a reboot; the card is partially functional (Bluetooth still works).
What to check. WiFi dropouts on the Z1 Extreme are reported with the MediaTek MT7922 card, often under Linux; a reboot is the usual workaround. Treat this as a driver/firmware issue rather than a dead card.
ROG Ally APU hard-locks at minimum TDP on wake from sleep (SteamOS 3.8)
On the SteamOS/Linux build, waking from sleep can lock the APU at ~4-7W, causing severe stutter until restart or AC re-plug.
What to check. This is specific to the SteamOS (Linux) configuration, not stock Windows. If running SteamOS on the Ally, a wake-from-sleep power hang is a known regression; a restart or AC re-plug recovers it.
These reports come from the pages linked under each item: owner forums, repair guides and workshops. They are not a diagnosis of any one unit, and a careful check of the one you are buying still applies.
Text from the Kriko Gaming consoles catalog, version 0.1.1, under the CC-BY-SA-4.0 license.