Hey folks!
Now I can confirm that the T1000E has a Flash Chip of 8192 KB. The trick is to set pin 45 high to enable the flash chip. Maybe it is also necessary to change #define PIN_QSPI_IO3 to (32) instead of (33). See pinout
/wiki.openelab.io/seeed-studio/sensecap-card-tracker#get-started
Until now I have no clue what this flash contains.