Does this mean that ( has left) can work in this sentence:
I haven't eaten anything since I have left home this morning.?
I think it must be ( left ) only because ( since ) could not be read meaning ( because) as in the above mentioned sentence in Cambridge.
I have another explanation, in Cambridge of English grammar,the author points out that the present perfect can be used in informal English to refer to completed events in the past.
The matter needs more clarification.
I'd be more grateful if other moderators could express their opinions.