Web browsers store information. A LOT of information.
99% of it is useless; I routinely spell-check by googling words like epilogue and antidisestablishmentarianism which do not need to appear in my browser history. They clutter the stuff I care about, like this stupid cable which I was looking at and forgot about, then realized it would make powering CPU fans a breeze and wanted to order it.
Firefox’s hisory clearing works from now -> last week, which is completely useless because it would remove my recent browsing history that I actually use:

I needed something to clear my history from last week -> January 1 1970, which led me to research how FF stores history data, and because sqlite is simple and awesome I threw a python script together to nuke old stuff:
#!/usr/bin/env python
import os, sys, subprocess
import sqlite3
from datetime import date, timedelta
import time
# Replace with your user profile, see about:profiles in the browser
PROFILE='/j/.mozilla/firefox/cfzbb6kw.default-release/'
if __name__ == '__main__':
db = f"{PROFILE}/places.sqlite"
conn = sqlite3.connect(db);
today = date.today()
last_week = today - timedelta(days=7)
# firefox stores times in epoch nanoseconds (epoch seconds * 1 million)
oldest_nanoseconds = int( time.mktime(last_week.timetuple()) ) * 1000000
print(f"oldest_nanoseconds={oldest_nanoseconds}");
# Remove all from moz_bookmarks_deleted
r = conn.execute("""
delete from moz_bookmarks_deleted where 1=1;
""")
print(f"moz_bookmarks_deleted r.rowcount={r.rowcount}")
# Trim moz_historyvisits
r = conn.execute(f"""
delete from moz_historyvisits where visit_date < {oldest_nanoseconds};
""")
print(f"moz_historyvisits r.rowcount={r.rowcount}")
# Trim moz_inputhistory
r = conn.execute("""
delete from moz_inputhistory where use_count < 4;
""")
print(f"moz_inputhistory r.rowcount={r.rowcount}")
conn.commit()
conn.close()
db = f"{PROFILE}/cookies.sqlite"
conn = sqlite3.connect(db);
# Remove cookies > 1 month old
r = conn.execute(f"""
delete from moz_cookies where creationTime < {oldest_nanoseconds};
""")
print(f"moz_cookies r.rowcount={r.rowcount}")
conn.commit()
conn.close()