This is the first Mac mini update in 10 years. Recently, I thought that the suspension and network surroundings were getting slower, but M1 was also coming out, so I updated it. The Mac mini is now the third generation. PowerPC-> Intel Core i5, it became M1. I bought a Thunderbolt 3 (USB-C) -Thunderbolt 2 adapter and a Thunderbolt-FireWire adapter to divert existing peripherals.
This time, I decided to stop restoring from Time Machine and install from scratch. I was worried about restoring the mail data, but since I had the mailbox on a different drive, I just re-entered the password and it returned to the original.