Looking at SO (https://stackoverflow.com/q/70226572/246801)

main.py

import re


# Replace embedded escaped unicode with their actual unicode values:
#
#   `\Not wanted backslashes\ unicode: \u2019\u2026`
#
# to:
#
#   `\Not wanted backslashes\ unicode: ’…`
#
# or:
#
#   `\u0061\u0070\u0070\u006c\u0065\u0073\u0020\u0026\u0020\u006f\u0072\u0061\u006e\u0067\u0065\u0073`
#
# to:
#
#   `apples & oranges`
#
# The "pure" unicode example of 'apples & oranges' could be decoded w/bytes.decode('unicode_escape'),
# but that won't work for the first example with back slashes


UNICODE_PTN = re.compile(r'\\u([\da-f]{4})')

s = '\\Not wanted backslashes\\ unicode: \\u2019\\u2026 || \\u0061\\u0070\\u0070\\u006c\\u0065\\u0073\\u0020\\u0026\\u0020\\u006f\\u0072\\u0061\\u006e\\u0067\\u0065\\u0073'

# As s is iterated, build a list of substrings: the unmodified slices between codepoints, and 
# the codepoints replaced with their unicode values
s_builder = []


s_start = 0
match = UNICODE_PTN.search(s, s_start)
while match:
    # Add unmodified slice between last start point and this match's start point
    s_builder.append(s[s_start:match.start()])

    # Convert matched codepoint to a char, and append
    codepoint = int(match.group(1), 16)
    char = chr(codepoint)
    s_builder.append(char)

    # Advance "start"
    s_start = match.end()

    # See if there are any more codepoints
    match = UNICODE_PTN.search(s, s_start)


new_s = ''.join(s_builder)
assert new_s == '\\Not wanted backslashes\\ unicode: ’… || apples & oranges'
print(new_s)