Is debnath belongs to scheduled caste?

Originally, Debnath probably used for people involved in priestly profession for people of Nath religion. The similarity can be traced in Buddhist also, where the intellectuals and priestly people were honored as "Debsarmana" or popularly as "Debsarma" or "Devsharma".
At a later date the descendants of Debnath also continued with the same .

Therefore Debnath are basically from priestly community.

However , due to various socio-economic condition and lack of literacy among them, made the Govt. of India to declare the entire community of Nath religion as backward communityvide ref as detailed below:

vide Notification F8(11)/99-2000/DSCST/SCP/OBC/2855 dated
**** vide Notification F8(6)/2000-2001/DSCST/SCP/OBC/11677 dated
05-02-2004 ***** vide Notification F8(6)/2000-2001/DSCST/SCP/OBC/11823 dated 14-11-2005,
(From OBC list published by Govt. of India, New Delhi)