Hi Edouard, sorry to hear that there are some recent problems getting Total Upkeep backups to complete properly on your website and our team will do everything we can to help!
Total Upkeep keeps a log for each backup attempt made on your website and the information in that log file will likely point us towards the cause of the recent backup failures. The log data is located under Total Upkeep > Tools > Logs in your WordPress dashboard, and we also have a guide in our support center that demonstrates how to find the log information for your website. Could you send us the log information from the most recent backup attempts? Once we see the logs we should have an idea of how to get backups working properly again.
Thank you for your patience while we get this sorted out and please let us know if you have any additional questions for us along the way!