Thank you Alex for your quick reply.
Yes, you are correct, I checked, and I found the cron nonce changed. It is strange because I updated much earlier an did not get any non success cron notification, and I found in the admin backend the wp-cron turned ON to three minutes (I had turned it to “never”).
I have a cron job for backups at night from my server. I dont think this is the reason, but I will check for tonight if it happens again this mistery.
Now, I changed the cron nonce and everything in order.