https://tetr.io/ - very well made multiplayer Tetris

Trash is subjective. Luanti can run on potatoes without an SSD. Worth a try: https://www.luanti.org/en/

This might seem controversial, but you can play chess, either lichess (open source) or chess.com (more popular).

I am not a browser gamer, but i played bonk.io for some time. Its a fun pvp platformer.

Additionally, you can also look for multiplayer indie games on itch. It does not have a lot of multiplayer browser games, but if the laptop is "really trashy", then running games natively should be faster than running them in browser.

https://geotastic.net/

It's geo guesser but not enshittified within an inch of its life. They have soooo many fun modes. McDonald's, tourist stuff, really obscure things. Good luck, and don't forget, it's probably fucking Russia anyway