My bird of paradise is showing signs of over watering (new leaf has brown and yellow edges) but one of my older leaves is dry, crispy and dead!
Just off the picture alone (which is not enough to be certain) my guess would be that the plant has root rot. You might want to check if the roots of the plant look healthy. My thought process for this guess is that the older leaves are very dry (roots probably rotted away and could not suck up enough water), while there are no signs of limping/wilting (this would be indicative of underwatering).
Again, as I mentioned before this is not certain and only my best guess going off of just the picture. If the roots look healthy, you will need to consider other possibilities (too much afternoon sun, heater dried the leaves out, ...) .