The phone does not accept a flash drive. When you access it, it reboots. What is the problem?

Question

Samsung

Yesterday I reflashed the phone and the phone stopped accepting the flash drive normally. Writes that it is damaged. Sometimes ask to connect. I click connect. Asks to format. I press format and at that moment the phone reboots. Previously, everything worked on the same firmware. Tried to install several others, but all the same. I went and bought a new USB flash drive, but the story is the same with it.
What could be the problem and how to solve it?