The string and array helpers moved out to a package

6.0’s only real breaking change is that the global str_ and array_ functions are gone, and the replacement is one Composer package away.

$ composer require laravel/helpers

# or, better, use the classes and stop using globals:
#   str_slug($title)        →  Str::slug($title)
#   array_get($a, 'k.j')    →  Arr::get($a, 'k.j')
#   str_random(32)          →  Str::random(32)

$ grep -rn 'str_|array_get|array_set' app/ | wc -l
214

Installing the compatibility package is the five-minute upgrade and it defers the work indefinitely, which is a legitimate choice for a large codebase under deadline. The reason to do the replacement instead is that global functions with those prefixes collide with PHP’s own — array_get may become a core function one day, and str_contains did in 8.0. A search and replace across two hundred call sites is an afternoon and it removes a category of future breakage.