public_html deleted by remote backup option

I was in the middle of transferring 4 websites from cyberpanel to another cyberpanel server using remote backup option. 3 transferred without any issue. in the middle of 4th one, I received an error(backup process killed and some other info) in the destination server logs on transfer. Then I check the source server and noticed my public_html folder of the website is gone from the source server. How could cyberpanel remote backup feature is doing something like that? The only difference between 3 successful transferred sites and the one failed, the one failed is little larger (about 6gb) and it has a subdomain. Subdomain content is left but the main domain whole public_html is gone. only the database left in the server.