Deco Mesh question, probably a dumb one

So a month or so ago I bought the x20 3-pack for my new house to get WiFi and wired options.

There’s currently 2 ethernet cables running through the house, both in the Living Room just in different corners (don’t ask, landlord has no idea why either)

Here in the Netherlands it’s common practice for the Internet Access Point to enter the house in your breaker closet, so that’s where my router/modem is, it’s a combo.

Right now the Deco’s are set up this way:

Main Deco: Living Room -> Router in Hallway through Ethernet Deco 2: Hallway -> Router Hallway through Ethernet Deco 3 Office -> Wireless, no ethernet possible

All of this works really well, wired units seem to get full speed and the wireless one seems to reach almost 500Mbps since we have Gigabit.

The only question is: does it matter that Deco 2 is hooked up to the router too? It’s not directly to the main unit but so far I haven’t seen any issues.

Using the units in Access Point mode by the way.

Looking for best set ups and tips if needed

Thanks!