I’ve moved this to Offtopic as we don’t support Lubuntu 20.04 LTS any longer.
Refer https://lubuntu.me/lubuntu-20-04-lts-end-of-life-and-current-support-statuses/ or on this site Lubuntu 20.04 LTS is End of Life
ps: If your system still reports as 20.04.3 then you’re well behind on applying security fixes. You can look here for the release of 20.04.6 but installed systems upgraded to it before that date as that date/link relates to the subsequent ISO release date. There is no flavors (like Lubuntu) mentioned in that release, as all flavors were EOL before 20.04.6 was required, but installed systems still upgraded to it. A system reporting as 20.04.3 would imply you’ve not upgraded your system since February 2022 or before so I hope you keep the system offline.