Some third party repositories are only offered over HTTPS and do not work when specified in build package.
For example InfluxData (provider of Telegraf) only serves over HTTPS and results in the following error during make:
Ign:1 https://repos.influxdata.com/debian buster InRelease Err:2 https://repos.influxdata.com/debian buster Release Certificate verification failed: The certificate is NOT trusted. The certificate issuer is unknown. Could not handshake: Error in the certificate verification. [IP: 54.230.72.81 443] ... W: https://repos.influxdata.com/debian/dists/buster/InRelease: No system certificates available. Try installing ca-certificates. W: https://repos.influxdata.com/debian/dists/buster/Release: No system certificates available. Try installing ca-certificates. E: The repository 'https://repos.influxdata.com/debian buster Release' does not have a Release file.
ca-certificates needs to be added to support public CA HTTPS verification.
Semi-related, apt-transport-https is depreciated in buster (bundled into apt ver 1.5+, ref: https://packages.debian.org/buster/apt-transport-https).