Network – Does my VPN leak or is it normal?

It's normal. See the last column Metric. If there are two routes to the same destination, the one with the lowest Metric the value has a lower cost and is chosen as the best alternative. On the other hand, the VPN tunnel itself needs a road for 0.0.0.0, as well.

Some (open) VPN implementations make additional measurements to choose from other connections. They divided the 0.0.0.0 for example. in two halves in addition to using low metric values. As this route is more specific, it is chosen more 0.0.0.0.

Network destination mask gateway interface metric
0.0.0.0 0.0.0.0 192.168.1.254 192.168.1.100 35
0.0.0.0 128.0.0.0 10.8.0.1 10.8.0.5 3
128.0.0.0 128.0.0.0 10.8.0.1 10.8.0.5 3

Similarly, you always see more specific routes, for example. for your physical networks:

                        192.168.1.0 255.255.255.0 On link 192.168.1.100 291

There you could leak information through various protocols, for example. mDNS, LLMNR, NetBIOS or SSDP, but this is another story and does not affect connections to the Internet via the VPN.