It is recalculated every six months. For simplicity let us assume the 7.12% April rate stays the same for 12 months.

$10,000 individual purchase. Interest is added monthly but it does not compound, ever. After one year you have earned $712 in interest. However, if you sell at this time you must pay 3-months interest which amounts to $178. Your net gain for the year is $534 for an actual rate of 5.34%.

5.34% is pretty good for a guaranteed return, but it is significantly less than people are expecting.

...especially people such as OP who decided to seemingly purchase a Series I bond on a whim.