DIAGNOSIS This is almost always a cable or connection issue, not the monitor failing. The signal is dropping out momentarily. The culprit is usually a cheap, damaged, or too-long cable that can't handle the QHD 144Hz bandwidth.
FIX Swap out your DisplayPort or HDMI cable. Use the one that came with the monitor if you aren't already. Unplug and firmly reseat it at both ends—monitor and GPU. Ensure it's fully clicked in. If you're using an adapter (like DisplayPort to HDMI), remove it; use a direct cable.
IF THAT DIDN'T WORK The issue could be related to power saving features conflicting. In the monitor OSD, go to 'Extra' and set 'Power Saving' to 'Off'. On Windows, go to Power & Sleep settings and set 'Screen and sleep' to 'Never' temporarily to test. Also, try lowering the refresh rate to 120Hz in Windows display settings to see if the dropouts stop, which would point to a bandwidth problem.
HEADS UP If you have multiple monitors connected, this can exacerbate handshake issues. Try running just the CQ27G2 alone to see if the blackouts stop. Some GPU drivers also have a known bug with multi-monitor setups and high refresh rates.