If a GRUB configuration contains variables with =, they are parsed improperly. For example:

set cmdline_extra="nosmt mitigations=off pci=nocrs"

is parsed by https://github.com/vyos/vyos-1x/blob/e3a04ea99108a2c4fbe1f95e93621fbf81bf750d/python/vyos/system/grub.py#L244 as:

{
    'cmdline_extra="nosmt mitigations=off pci': 'nocrs'
}

The problem is in regex: https://github.com/vyos/vyos-1x/blob/e3a04ea99108a2c4fbe1f95e93621fbf81bf750d/python/vyos/system/grub.py#L52

In a very rare but real cases this can break config files.