Mircophone components can’t record forever - there is a “buffer” with a finite size which will eventually fill up. As you requested for a Microphone component to continue recording forever (by leaving the Stop field blank), PsychoPy has substituted in the maximum time which you Microphone can record for, given the size of its buffer and the sample rate it records at.
>2023.1.0
No action is needed! Your Mircophone component will record for as long as it is able. To silence this alert, simply give your Microphone component a duration.