git lfs not working with github / ssh issue

I have a new repository with no commits. I'm not having issues with files that were committed to git and moving them to lfs.

> git version
git version 2.39.3 (Apple Git-145)
> git lfs version            
git-lfs/3.6.1 (GitHub; darwin arm64; go 1.23.4)

This illustrates the problem.

> git init
> git lfs track "*.db"
> cat .gitattributes 
*.db filter=lfs diff=lfs merge=lfs -text
> git add .gitattributes
> git commit -m "init"
...
> git add mybigfile.db
> git lfs status
On branch main

Objects to be committed:

    mybigfile.db (Git: 09539d3)

Objects not staged for commit:


> git commit -m "add .db"
...
> git lfs ls-files
(nothing printed here)
> git remote add origin [email protected]:username/myrepo.git 
> git push -u origin main
Errors (large file must be on LFS etc)

remote: error: Trace: 8f76...
remote: error: See https://gh.io/lfs for more information.
remote: error: File mybigfile.db is 157.89 MB; this exceeds GitHub's file size limit of 100.00 MB
remote: error: GH001: Large files detected. You may want to try Git Large File Storage - https://git-lfs.github.com.
To github.com:username/myrepo.git
 ! [remote rejected] main -> main (pre-receive hook declined)
error: failed to push some refs to 'github.com:username/myrepo.git'

What I tried:

GIT_TRACE=1 git push (or GIT_CURL_VERBOSE=1);

20:43:44.031634 trace git-lfs: pure SSH connection unsuccessful (#0)
20:43:44.031676 trace git-lfs: pure SSH protocol connection failed (upload, origin): Unable to negotiate version with remote side (unable to read capabilities): EOF
Failed to connect to remote SSH server: Invalid command: git-lfs-transfer ThomasJannaud/app-langues.git upload
  You appear to be using ssh to clone a git:// URL.
  Make sure your core.gitProxy config option and the
  GIT_PROXY_COMMAND environment variable are NOT set.

• git:// through proxy and https://github.com/git-lfs/git-lfs/issues/5893

ssh [email protected] "git-lfs-authenticate xxx/myrepo.git upload" returns a nice json with an authorization and http code 200

> git config --global url.https://github.com/.insteadOf git://github.com/

So somehow git push to github with lfs needs ssh, it says ssh is not working, and when I try in a separate command it works. Doing something very vanilla and following the instructions, I'm at a loss :( Any help greatly appreciated, thanks

Update:

> git remote -v     
origin  [email protected]:username/myrepo.git (fetch)
origin  [email protected]:username/myrepo.git (push)

> git config --list --show-origin
file:/Applications/Xcode.app/Contents/Developer/usr/share/git-core/gitconfig    credential.helper=osxkeychain
file:/Applications/Xcode.app/Contents/Developer/usr/share/git-core/gitconfig    init.defaultbranch=main
file:/Users/thomas/.gitconfig   user.name=Thomas
file:/Users/thomas/.gitconfig   user.email=myemail@...
file:/Users/thomas/.gitconfig   url.https://github.com/.insteadof=git://github.com/
file:.git/config        core.repositoryformatversion=0
file:.git/config        core.filemode=true
file:.git/config        core.bare=false
file:.git/config        core.logallrefupdates=true
file:.git/config        core.ignorecase=true
file:.git/config        core.precomposeunicode=true
file:.git/config        lfs.repositoryformatversion=0
file:.git/config        [email protected]:username/myrepo.git
file:.git/config        remote.origin.fetch=+refs/heads/*:refs/remotes/origin/*
file:.git/config        branch.master.remote=origin
file:.git/config        branch.master.merge=refs/heads/master