I had the same issue with LZ4. I found a thread about it on the Linux Mint Debia...

I had the same issue with LZ4. I found a thread about it on the Linux Mint Debian Edition forum and posted my fix there: https://forums.linuxmint.com/viewtopic.php?p=2767087#p276708....

In short: add the kernel modules and update GRUB as usual, then install sysfsutils and add the following line at the end of `/etc/sysfs.conf`:

  module/zswap/parameters/compressor = lz4
  # For zstd:
  #module/zswap/parameters/compressor = zstd

Perhaps some kernel change between Linux 6.8 and 6.12 caused the old approach to no longer work.