Did you try to flash Android 11 with Odin ?
If not download the last standard "Odin3 v3.14.1"
here.
Download your Android 11 firmware and decompress it.
You should get 4 files : 1 starting name with "AP", 1 starting with "BL", 1 starting with "HOME_CSC" and 1 starting with "CSC_"
Boot your tablet in download mode (from off, volume up and down at same time and plug usb cable connected on your computer) wait the blue screen to appear, then one time volume up to enter download mode.
Open Odin with admin rights and select the square for "BL" then click on "BL" and choose the file starting with "BL" from your firmware. Repeat the process for "AP" and "CSC" (for CSC choose the file starting with "CSC_" to factory reset the tablet at the same time).
Check that only the options "Auto reboot" and "F. Reset time" are checked.
Click on start and wait the flashing process end with a green pass square.
Your tablet will auto reboot and you can close Odin.