Its cold. You should check your tire pressure
Your tires aren't "losing" air, it's just contracting - here's the crux of the matter (from article):
Gas expands with heat and contracts with cold. So when winter arrives, it's best to check in on your tire pressure for safety.
Tire pressure drops by one to two pounds per square inch for every 10 degrees.
...... just two days it went from 33 PSI to 25.
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I revise my comment - on that tire, you likely have an actual leak!