@Yusuf Azad Thank you for reaching out to Microsoft Q&A. Apologize for the inconvenience caused on this.
As mentioned here in this documentation, currently we have a limitation to run the diagnose and solve problems/app service diagnostics for 24hours time period only.
Your feedback is noted, and I have relayed the feedback internally to our product engineering team.
We also have a feedback item on this, if you wish you may upvote on the Uservoice post - All of the feedback, you share in these forums will be monitored and reviewed by the Microsoft engineering teams responsible for building.
Feel free to reach back to me if you have any further questions on this.