I recently asked about what happens when you lose requirements for an attuned item (here). Now, I have a slightly different but still related question involving the artificer class' 20th-level ability, which says that you can
use your reaction to end one of your artificer infusions
One of the artificer infusions is the Belt of Hill Giant Strength, which sets your Strength score to 21. Since heavy armor has a Strength score requirement, what happens if I un-attune to the belt by ending the infusion and lose the required Strength to wear armor that I have equipped?