ASUS USB-C2500 2.5G Ethernet Adapter (90IG0650-MA0R0T)

Name: ASUS USB-C2500 2.5G Ethernet Adapter (90IG0650-MA0R0T)
Brand: ASUS

This is what matters about ASUS USB-C2500 2.5G Ethernet Adapter (90IG0650-MA0R0T).

About

Likely built on a Realtek RTL8156BG (confirmed via hardware IDs in the wild, not an official ASUS spec) inside a nylon-braided, fingerprint-resistant aluminum shell. Native plug-and-play on macOS and Linux; Windows auto-installs a driver. Despite its "USB-C2500" name, it terminates in a physical USB Type-A connector, requiring a second USB-C adapter to use on Steam Deck, ROG Ally or Legion Go.

Ports: 1× Ethernet (2.5GBASE-T) and 1× USB-A (fixed cable — despite the product name, no USB-C connector)

Confirmed with

Notebook (generic)
Recommended specifically to avoid the high-CPU-usage bug of older RTL8153 (1G) chips under macOS: "Buy the ASUS 2.5G USB-A adapter especially if you plan to use it with macOS as the 1G driver causes high CPU usage in macOS."