Paths in /etc/paths.d are not expanded for all shells.
dotnet adds a /etc/paths.d/dotnet-cli-tools file that contains
~/.dotnet/tools
The ~/.dotnet/tools folder is used for tools that are 'global' across all projects for the same user.
The tilde is not expanded for zsh and executables installed to ~/.dotnet/tools will not be found via the PATH. $HOME/dotnet/tools is also not expanded. (There appears to be a difference with bash. bash does seem to expand the tilde but doesn't expand variables.)
The man page for path_helper says
Files in these directories should contain one path element per line.
The /etc/paths.d mechanism is great. Keeping installers out of a user's .profile/.zprofile/.zshrc/etc files is very helpful. But user home directory paths for the current user are not supported (at least not consistently across all shells) in the current implementation of path_helper and paths.d.
Not expanding paths might be by design or by omission but adding support for paths in the current user home would be useful.