Brittle CR-PETG Model

Ender Series General Discussions
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I recently bought a Creality Ender-V3 KE in a bundle with 2Kg of filament. There was no choice of filament and the machine came with 2 reels of black CR-PETG .
Today I reprinted an SD Card holder and accidentally dropped it onto a hard floor. To my surprise a piece of the bottom of the model broke off.
I used Creality Print 6, with the default settings for this filament, why did it break?

DSC08974
DSC089741920×1440 207 KB

Thanks in advance,
Steve