If you note https://lubuntu.me/lubuntu-20-04-lts-end-of-life-and-current-support-statuses/ it says rather clearly that Lubuntu 20.04 LTS is end of life and unsupported.
Releases later than 20.10 vary as per all Ubuntu ISOs, as Ubuntu decided to have all architectures boot the same way for a release; which can mandate slight changes in the ISO and how booting occurs. If the ISO is cloned or written unchanged to install media, you won’t have problems, however if options are used to reformat the ISO during write to install media; the options used must match the specific release being used & release being written; which mandates the ISO writing software be updated so it can deal with that specific release.
Your details refer mostly to an unsupported release that we won’t do anything about, and for 24.04 you gave no specifics & thus we cannot rule out user procedure error.
Did you verify ISO on download as per manual as that is what detects flaws in the download; for the ISO write the method used matters; especially on releases of 20.10 or later (though Lubuntu and all flavors will using the same methods as Ubuntu Desktop/Server).
In the tags you’ve put this against 20.04; so I’ll move this to off-topic as we don’t support that release sorry.