It shouldnt be a problem on smaller servers or servers with fast skill gain (because you will reach SI level 7 anyways), but server with a high population and high/exponentially increasing requirements for more stars. The diet of the people on these servers will be mostly charred fish and meat for the first 2-3 days, so their XP multiplier will be abyssmal if they do much of the work necessary to get stuff moving. But they will still do a lot of it and by that leveling up their professions (which is good), but as Self Improvement is tied to the XP multiplier they will earn much less XP for Self Improvement than the people who are just sitting out that period and are then able to eat the good food after gatherers brought in the first harvests. I know its a small problem and niche situation that happens in, but it also affects those jobs that profit the most from the self improvement perks the most. Namely Hunter, Miner and Logger.
Dennis Scholz If you take a profession early on in the servers cycle when only tier 1 food and tier 1 materials are available and then level that skill all the way up to level 7 you will earn much less Self Improv. XP compared to a person that joined the server when T3 cooking and T3 materials are available and picked the same skill and leveled it to 7. Roughly 2.5x-3x less self improv XP. Self Improv XP earned on profession lvl-ups should be a static value and not scale with current players XP. That would solve the issue.
Can you describe how they are punished? They will always have a higher total XP than someone joining later as long as they continue to play and optimize? There might be a calculation bug or the system not working as intended to begin with.