>>> import re

# should match
>>> regex = re.compile("[\ua7aa-\uffff]", re.IGNORECASE)
>>> print(regex.match("\u0266"))
<re.Match object; span=(0, 1), match='ɦ'> 

# should not match
>>> regex = re.compile("[\ua7aa-\U00010000]", re.ASCII | re.IGNORECASE)
>>> print(regex.match("\u0266"))
<re.Match object; span=(0, 1), match='ɦ'>

# must be related to case folding, since \ua7aa folds to \u0266
>>> regex = re.compile("[\ua7ab-\U00010000]", re.ASCII | re.IGNORECASE)
>>> print(regex.match("\u0266"))
None

# correct behavior when upper bound is in BMP
>>> regex = re.compile("[\ua7aa-\uffff]", re.ASCII | re.IGNORECASE)
>>> print(regex.match("\u0266"))
None