I'm seeing much more than that, installing on noble:

Setting up onboard (1.4.1-5ubuntu2) ...
/usr/lib/python3/dist-packages/Onboard/Appearance.py:924: SyntaxWarning: invalid escape sequence '\w'
  _key_ids_pattern = re.compile('[\w-]+(?:[.][\w-]+)?', re.UNICODE)
/usr/lib/python3/dist-packages/Onboard/Appearance.py:1066: SyntaxWarning: invalid escape sequence '\w'
  key_ids = [x for x in re.findall('\w+(?:[.][\w-]+)?', text) if x]
/usr/lib/python3/dist-packages/Onboard/LayoutLoaderSVG.py:98: SyntaxWarning: invalid escape sequence '\('
  self._layout_regex = re.compile("([^\(]+) (?: \( ([^\)]*) \) )?",
/usr/lib/python3/dist-packages/Onboard/LayoutLoaderSVG.py:447: SyntaxWarning: 'str' object is not callable; perhaps you missed a comma?
  raise Exceptions.LayoutFileError("Unrecognized modifier %s in" \
/usr/lib/python3/dist-packages/Onboard/SpellChecker.py:324: SyntaxWarning: invalid escape sequence '\s'
  SPLITWORDS = re.compile("[^-_\s]+", re.UNICODE|re.DOTALL)
/usr/lib/python3/dist-packages/Onboard/TextDomain.py:144: SyntaxWarning: invalid escape sequence '\s'
  strings = re.split('(\s+)', context)
/usr/lib/python3/dist-packages/Onboard/TextDomain.py:161: SyntaxWarning: invalid escape sequence '\s'
  """
/usr/lib/python3/dist-packages/Onboard/TextDomain.py:291: SyntaxWarning: invalid escape sequence '\s'
  _growth_sections_pattern = re.compile("[^\s?#@]+", re.DOTALL)
/usr/lib/python3/dist-packages/Onboard/TextDomain.py:447: SyntaxWarning: invalid escape sequence '\['
  "^In \[[0-9]*\]: ",   # ipython
/usr/lib/python3/dist-packages/Onboard/TextDomain.py:450: SyntaxWarning: invalid escape sequence '\?'
  "^\?",                # vi reverse search
/usr/lib/python3/dist-packages/Onboard/TextDomain.py:451: SyntaxWarning: invalid escape sequence '\$'
  "\$ ",                # generic prompt
/usr/lib/python3/dist-packages/Onboard/TextDomain.py:459: SyntaxWarning: invalid escape sequence '\('
  "^\(.*\)`.*': ",  # bash incremental search
/usr/lib/python3/dist-packages/Onboard/TextDomain.py:739: SyntaxWarning: invalid escape sequence '\w'
  _url_pattern = re.compile("([\w-]+)|(\W+)", re.UNICODE)
/usr/lib/python3/dist-packages/Onboard/WordSuggestions.py:1253: SyntaxWarning: invalid escape sequence '\S'
  _section_begin_pattern = re.compile("\S*\s*$")
/usr/lib/python3/dist-packages/Onboard/WordSuggestions.py:1254: SyntaxWarning: invalid escape sequence '\S'
  _section_end_pattern = re.compile("\S*(?=\s*)")
/usr/lib/python3/dist-packages/Onboard/pypredict/lm_wrapper.py:302: SyntaxWarning: invalid escape sequence '\s'
  """ .*?
/usr/lib/python3/dist-packages/Onboard/pypredict/lm_wrapper.py:368: SyntaxWarning: invalid escape sequence '\s'
  tokenize_pattern = """
/usr/lib/python3/dist-packages/Onboard/pypredict/lm_wrapper.py:467: SyntaxWarning: invalid escape sequence '\w'
  if not re.match("""
/usr/lib/python3/dist-packages/Onboard/pypredict/lm_wrapper.py:504: SyntaxWarning: invalid escape sequence '\d'
  result = re.search("ngram (\d+)=\d+", line)
/usr/lib/python3/dist-packages/Onboard/pypredict/lm_wrapper.py:624: SyntaxWarning: invalid escape sequence '\w'
  target_word = re.search("^([\w]|[-'])*", prefix_to_end, re.UNICODE).group()
/usr/lib/python3/dist-packages/Onboard/utils.py:151: SyntaxWarning: invalid escape sequence '\d'
  """
/usr/lib/python3/dist-packages/Onboard/utils.py:220: SyntaxWarning: invalid escape sequence '\s'
  pattern = re.compile('>\n\s+([^<>\s].*?)\n\s+</', re.DOTALL)
/usr/lib/python3/dist-packages/Onboard/utils.py:221: SyntaxWarning: invalid escape sequence '\g'
  pretty_xml = pattern.sub('>\g<1></', ugly_xml)
/usr/lib/python3/dist-packages/Onboard/utils.py:356: SyntaxWarning: invalid escape sequence '\:'
  """
/usr/lib/python3/dist-packages/Onboard/utils.py:1542: SyntaxWarning: invalid escape sequence '\w'
  """(?:
Setting up catfish (4.16.4-2) ...