if i hold 12500 fun token, after 30 days if i hold bitcoin i get 2,5+4,08% - total 6,58% profit and after 90 days 9% interest on bitcoin or no?
No. You won't get an additional interest of 2.5%.
Your interest you get now will increase by 2.5%. This means that your interest rate will be multiplied by 1.025.
So, in the case you hold 12,500 FUN tokens, after 30 days, your annual interest rate will increase to 4.182.