I bought one of those too. I’m returning it tho - i thought it was crap!
But maybe that’s my lack of experience showing
It had a terrible wind up and down thing in the motor when in oscillation mode which made so much noise... lie an engine tryin to get uphill and then down and the speed of the fan would go waaay fast and then waaay slow. Seemed to be labouring a lot. Also the low setting was almost as fast and hard as the high setting. It felt to me like it would break any second. Apart from anything else, it is just too noisy for me.
Anyway - I’m glad you all find it ok. You sparkys in here, is there anything about the mains power supply that could cause the motor to wind up and down like that? Or is it something faulty in the fan motor making that happen?