there is no "lemmy TOS". lemmy is only a piece of software that can be ran on a server. it is licensed under the GNU Affero GPL, a copyleft free software license.

this means that pretty much the only legal "terms" you need to abide to run the software on a server is that if you modify it in any way, you have to publish the source code so that others can freely read and modify your version, the way you read and modified the original (this is what copyleft means; it's the exact opposite of copyright).

the instance owner is the only one providing any "service" here, and as such they decide their terms (the site-wide rules for an instance). if you run your own instance on your own server, you are the only one who can dictate any "terms of service".

all of this is by design; the fediverse would be pretty useless if anyone could impose a global "terms of service" over it.