For the ohms to drop by half is not normal.
My guess is a 510 centerpin insulator problem.
It can be a pain working that top pressfit off for the first time to change the insulator with a better one but if you're in an area where there's no
vape shops it might be worth it.
or on the other hand it might just be the atomizer coil shorting out on one side with the metal around it.
You need to isolate whether the ohms dropping from 1.9 to 1.1 is because of a 510 centerpin problem or from something happening on the topper itself. Screwing/unscrewing the 510 connector and checking ohms can give an indication whether its the connector.