The TAJK226K004RNJ: This is a 22 µF tantalum capacitor rated at 4 V DC, in a molded 1206 (3216 Metric) surface-mount package. The 1.8 Ohm ESR is the series resistance that governs ripple current heating and output ripple voltage — for a 100 kHz switching regulator output, that ESR adds about 40 mV of ripple per 22 mA of AC ripple current, which is high enough to matter in a low-noise rail.
The molded case handles the thermal cycling without the mechanical stress that can crack conformally-coated wet tantalums.
Package footprint and board-fit note
The 1206 case measures 3.20 mm x 1.60 mm with a seated height of 1.00 mm max. That low profile fits under a 1.2 mm clearance, but the 1.0 mm height means the pick-and-place nozzle must be set for a thin component — standard 1206 chip capacitors are typically 1.6 mm tall, so the feeder tape pocket depth and nozzle vacuum pressure should be verified during setup to avoid tombstoning.