Not exactly urgent, but using:
"php": "^7.2.5",
"beyondcode/laravel-websockets": "^1.6",
"fideloper/proxy": "^4.2",
"fruitcake/laravel-cors": "^2.0",
"guzzlehttp/guzzle": "^6.3",
"laravel/framework": "^7.24",
"laravel/tinker": "^2.0"
And a max message size of 250kb, I can send a message of over 300kb, via the PHP API, and it is all received in my browser via the websocket.