Ubuntu is based on Debian, but it differs in quite a lot of ways.
Probably, they didn’t use dkms to install their custom wifi driver. If that was the case, Debian and Ubuntu behave identically and the driver isn’t added if a newer updated kernel is installed.
Especially if you use Ubuntu’s 6-monthly releases.
If their driver was included in a user PPA, it’s gone after a Ubuntu release upgrade and the sources.list of the PPA is deleted.
Probably, they didn’t use dkms to install their custom wifi driver. If that was the case, Debian and Ubuntu behave identically and the driver isn’t added if a newer updated kernel is installed.
If their driver was included in a user PPA, it’s gone after a Ubuntu release upgrade and the sources.list of the PPA is deleted.
IME PPA-sources.lists get disabled, not deleted.