The content described in the post does exist in the previous version, we submitted an update in the early stage, which should have fixed this kind of problem, you can open the internal update in the update settings of the control center, and try to update the system once to see if it's already in the latest version, the problem may not have been completely solved, I hope that this information can help you in some way, and if the latest version has not been thoroughly repaired, please also reply, and we will analyze it further, thank you very much.

Thanks for your reply. All applications and the system are updated to the latest versions. Additional information: Laptop Lenovo ThinkPad E 15 Gen 3 AMD, Deepin 20 (Community 20.9), 5.15.77-amd 64-Desktop.
It seems that this appeared a few months ago, I will not say more precisely.

Hello. I want to add to the previous message. When a dark theme is not selected as a system theme, its selection in the application is not saved when you restart applications: file manager, notepad, calculator, music, control center - not only in the terminal.

Go to the Control Center - Update - Update settings, turn on the beta channel, then update the beta, and restart after the update.

Thanks for the offer, but I won't be able to join the Deepin testing community on the main machine. 🙁

Hello. After today's update, the dark theme saves in the terminal and other applications. Thank you very much for your work!