Checksum in Volumes and Bit Rot Protection in Shares

Hello, new owner of RN204 here.

I am struggling to find an explanation what Checksum setting (unticked by default in 6.3.4 I have) does. I am guessing it enables NAS doing checksums on the files but what does it actually mean for me in terms of keeping the data safe, performance (I presume only write performance will take a hit?) and how does that interact and/or complement the Bit Rot Protection I can activate per individual shares (I understand it also does checksums?)?
Also I am curious as to why it is not enabled by default, as it sounds to be a useful feature for keeping the data safe?



I am planning to have Bit Rot Protection enabled (and this one of the main reasons I chose a Netgear NAS (using BTRFS) over competitors') - does this mean I should or should not also enable Checksums in Volumes?



Thank you, and I apologise if this has been previously answered (I tried my best to search before asking here).