It may be. But it could be an iPhone charger 4 rooms away. If you can, use a longer ethernet cable and move the powerline adapter to a different outlet.
But an 89Mbit link rate should give you better than 10Mbit.
You motherboard has 2.5Gb ethernet. Those have had problems. That is a Realtek rather than the Intel 2.5Gb ethernet.
There are other posts on this board where the performance of that port is poor -- https://forums.tomshardware.com/thr...-boards-with-realtek-2-5g-controller.3645659/
I would DEFINITELY recommend you be sure you have the latest driver. There is one dated mid Feb on the support page Version 10.42.526.2020 .
I would also recommend that you buy a long ethernet cable (or temporarily move your rig to the router) and test with a direct cable. There are two possible problem areas and the only way to eliminate the powerline adapters is to use a commercial network cable direct to the router.