Weird QA_PIXEL cloud masking values

[cgmorton]

Just wanted to document some weird QA_PIXEL (and pixel_qa) values. These seem to be related/correlated to images that are along the coast, but I'm not sure about that yet. For reference I'm copying the QA_PIXEL bit map below.

0000000000000001  # Designated Fill
0000000000000010  # Dilated Cloud
0000000000000100  # Cirrus
0000000000001000  # Cloud
0000000000010000  # Cloud Shadow
0000000000100000  # Snow
0000000001000000  # Clear
0000000010000000  # Water
0000001100000000  # Cloud Confidence
0000110000000000  # Shadow Confidence
0011000000000000  # Snow/Ice Confidence
1100000000000000  # Cirrus Confidence

LANDSAT/LE07/C02/T1_L2/LE07_041037_20140609
https://code.earthengine.google.com/c571583a8da4243e9f27609ecc455b3b
The "clear" pixels have QA_PIXEL values of 7440, which maps to 0001110100010000 and is a high confidence shadow.

LANDSAT/LC08/C02/T1_L2/LC08_044035_20190823
https://code.earthengine.google.com/145c0b088846e90d7facd14ef143d37c
The "clear" pixels in this image have QA_PIXEL values of 23888, which maps to 101110101010000 and is a high confidence shadow but also has the clear bit set True.