The short answer is No. They shouldn’t need compression to absorb.
The complicated answer is that some cloth diapers use additional materials that kind of need some sort of pressure on them to force the liquid through the membrane.
The good answer is most kids have a heavy enough flow to do this when they pee that there isn’t this need for the child to be sitting or the diaper to be super close to the body.
Some of these textiles include mediocre microsuede, microfleece, polar fleece, and sometimes microfibre on it’s own.
You can see this happen with a few of my inserts – coffee bamboo, microfibre, fleece lined diapers. It does make a difference if it’s a spritz versus a flow.
Personally, I think if this is happening fairly regularly its because the cloth diaper manufacturer has let you down by creating a subpar mediocre product that doesn’t meet the actual needs of the consumer.
Most other natural fibres people put in cloth diapers don’t need compression and this means you can put the diaper on with a terrible fit experience and still end up with a positive cloth diaper experience without immediate leaks and headaches.
How do I know if lack of compression is the reason for my diaper leaky? Honestly, you don’t. Because the chances are your diaper is leaking because of poor fit over compression. Sure, if the insert is too far away from your child when they pee then you could have an issue where the flow isn’t fast enough to penetrate the fibres. But if the diaper is this far away from the body of your child there’s a good chance you have a poor fit. A diaper should fit nice and tight like undies, not like bloomers.
How do I fix it? Get a nice good fit on your diaper, or get new inserts that don’t need that kind of compression. Once the insert is wet it doesn’t need the same sort of pressure and will absorb.
So yeah, some diapers need compression to absorb but it really shouldn’t. Cloth diaper manufacturers need to stop making this kind of product it’s frustrating to the consumer and a great to experience leaks.