Hi, in which context are you referring to the 'hashes'?
If you're asking about the hashes for required packages in 'Chapter 3. Packages and Patched', the hashes should match if you're downloading from the provided mirror - https://www.linuxfromscratch.org/lfs/mirrors.html#files
Downloading from these mirrors ensures that you have the exact version needed for the build, in any other cases you run the risk of the system not working as expected / documented in the book.
If you're asking about the hashes for required packages in 'Chapter 3. Packages and Patched', the hashes should match if you're downloading from the provided mirror - https://www.linuxfromscratch.org/lfs/mirrors.html#files
Downloading from these mirrors ensures that you have the exact version needed for the build, in any other cases you run the risk of the system not working as expected / documented in the book.