is this not maintained any longer?

[dcindallas]

❯ flavours update all
remote: Repository not found.
fatal: repository 'https://github.com/aramisgithub/base16-solarized-scheme/' not found
remote: Repository not found.
fatal: repository 'https://github.com/isaacwhanson/base16-qualia-scheme/' not found
remote: Repository not found.
fatal: repository 'https://github.com/aramisgithub/base16-ia-scheme/' not found
fatal: cannot change to '/home/duane/.local/share/flavours/base16/schemes/solarized': No such file or directory
fatal: cannot change to '/home/duane/.local/share/flavours/base16/schemes/qualia': No such file or directory
fatal: cannot change to '/home/duane/.local/share/flavours/base16/schemes/ia': No such file or directory
error: RPC failed; curl 92 HTTP/2 stream 5 was not closed cleanly: CANCEL (err 8)
error: 2326 bytes of body are still expected
fetch-pack: unexpected disconnect while reading sideband packet
fatal: early EOF
fatal: fetch-pack: invalid index-pack output
fatal: cannot change to '/home/duane/.local/share/flavours/base16/schemes/summercamp': No such file or directory
Error: Git failed to run on repository 'https://github.com/aramisgithub/base16-ia-scheme'. Check if your repo list is valid.

[titaniumtraveler]

That issue is more about the scheme source that is being used as default is https://github.com/chriskempson/base16-schemes-source.git, which links a lot of invalid sources.
You can go into ~/.local/share/flavours/base16/sources.yaml and remove the offending sources and update the schemes using flavours update schemes.

It is not ideal, but it solves it.

(Also please put error messages into code blocks.)