The laptop Spec looks very decent so that is not the issue.
Maybe the driver is the issue or the Ethernet cable. You may want to change the cable first to see if you get different results.
Do you have another laptop or desktop to try? If not then it is difficult to carry out the experiment suggested by Mach.2 (to test internal home network first before testing internet speed). The good thing is that you have two 10G NICs and 10G switches. Just need another capable laptop/desktop.
I tend to believe the connection between the router and ONT is okay. So the issue is between the laptop external 10G adapter and the router or ONT (if you bypass the router).
At this kind of time, you may appreciate the more advanced routers which can have SSH access and more diagnostic functions, like the Asus routers (which can show the health of the LAN port connections) or mini PC based router running pfSense/OPNsense/OpenWRT (bare metal or virtualized) or MikroTik 10G capable routers. In this case, at least you can easily check if the connection from router to Internet is okay, say by running SpeedTest from the router (Asus router CPU may not be fast enough to get 8.2Gbps but you get the rough information).
To me (more aligned to the power users) the three TP-Link WiFi 7 routers given by three ISPs are more suitable as a 10G capable AP. SingTel already configure the HB810 as AP but the ZTE XGS-PON ONR is also not feature rich. Starhub issued EB810v and MyRepublic issued Archer BE805 may be okay as the main router for average 10G plan users, but not that great for power users.