What is the meaning of current binary in download mode ?

[Android Central Question]

After I root my phone (Samsung galaxy Note 8 SM-N950F) in download mode it shows my current binary is custom when i search it in internet I found that it means I had installed a custom rom but I didn't install any custom rom. But I rooted my phone by TWRP recovery with MAGISK.
And also it didn't show system status
please help me
My phone is Samsung galaxy note 8 SM-N950F