it's been over filled, no? when there's too much oil in the oil pan,
it'll be beaten by the crankshaft and turns into a foam. trust the dip
stick, not the haynes manuals. they are often clueless about your
car's oil pan capacity and your oil filter size.

foam is mostly air, it reduces oil pressure, which may cause the oil
lamp to come on, which may cause you to add more oil, which definitely
will cause more foam.
and since foam is mostly air... and so on

I noticed some bubles when I change the engine oil. Is this normal?

Thanks