Currently if you do the command /cars=all then followed by the command /cars-=skin_id you would get all LFS cars to be selectable except the one that we excluded with the skin id. One would expect that the /mods command would have the same behavior but that doesnt seem to be the case.
If you execute the /mods=all command and then execute /mods-=skin_id command, it would ignore the second (-=) command.
The /mods-=skin_id command only works after you have defined a list such as /mods=C52608+B7B8DC.

This is how I think it works - when you run /mods all, there is no whitelist, because it would have to be updated every time there’s a new mod or a mod is deleted, so it’s more of s on/off switch. Also, I believe the mods whitelist is limited to 120, so “all” minus one would totally exceed that limit.

To solve this, there would have to be a blacklist command, where you would set disallowed mods instead.