According to this page
https://www.eevblog.com/forum/beginn...ll-capacitors/
your ESR meter may be reading the capacitive reactance of small capacitors in series with the resistance.
In fact, if you plug in 0.1 uf and the frequency of your tester (100 kHz) on this page
https://www.omnicalculator.com/physi...tive-reactance
You get 15.9 ohms