Tangia REP is calculated from your Bits/Tangia Token earnings and REP generated from interactions shared to the Tangia Community on a rolling 30 basis which means your REP level will go up or down based on usage.
It is normal for your REP level to decrease
Affiliate and Partner status unlocks are permanent, your REP can still decrease, but you will never lose affiliate/partner perks as long as you are still using Tangia.
Why does REP decrease?
The REP system was designed to dynamically allocate reserve characters for the AI TTS and ASK AI. Reserve characters are consumed only when channel point TTS or ASK AI interactions are redeemed. REP gives us the ability to double the benefits of bit/token interaction redeems by increasing your reserve allocation without you having to purchase additional reserve characters or Tangia+. But because of the costs associated with the TTS we cannot make the allocation increases permanent as its just not sustainable. You can read more about Reserve Characters here.