It is recommended you update ASAP if you are on versions 2.1.22 or 2.1.23 due to an exploit vulnerability that was patched in 2.1.24.

If you haven't updated in a while, please read the changelog for 2.1.22 & 2.1.23

Version 2.1.25

• Shake now has an upper limit of damage (10) - Will be configurable in 2.2 which is coming in the near future
• Rank 1 of Catalysis & Concoctions are now available at level 0 by default (update skillranks.yml or delete it to regen a new one)
• NOTE: The change to shake was to make mcMMO more compatible with plugins that spawn entities with large amounts of HP
  

The alchemy fix is because rank 1 for Alchemy skills are kind of required to get going in that skill, so it didn't make much sense to give it steep requirements.

Update skillranks.yml manually or delete it to regen a new one