Hey @theo,
It looks like you are using queue mode, Are you running with multiple webhook hookers and have you checked your workers to make sure they are on the same version of n8n and that nothing odd is showing in their logs?
Without seeing the workflow JSON I can’t see what node versions you are using but it could be that the main instance is on a newer version of n8n that has a newer webhook version and the worker doesn’t have it available.