Seems fairly normal to me.

Although, I drive a manual, the engine does seem to do its own sort of 'braking' (different to just losing speed while not accelerating).

And it's not abrupt or random, it's a constant braking. I've noticed if I let the car roll while in gear, the engine will slow the car down itself, but when I get to a very low speed/revs (under 10-15kph), the engine seems to 'let go' (as if it put itself in neutral) and it only slows down by losing inertia, at this point I have to brake to come to a stop or i keep rolling lol.