I took a quick look at their manual. This stood out to me:
CAUTION! Do not touch the fan blade whew removing the multi-layer filter.
Maybe you can take the filter canister out, turn the unit upside down, and then add a few drops of your favorite lubricant to the motor or bearings.
I’m guessing though — perhaps you can’t easily access that area from the filter area. Take a peek and see.
That reminds me, I need to do this on my Levoit air purifier, too.