PHPUnit 7 changed the assertion you use most

7.0 landed in February and deprecated a set of assertions that appear in almost every suite, with removals following in 8 — so the warnings are a deadline rather than noise.

// deprecated in 7
$this->assertInternalType('array', $result);
$this->assertArraySubset(['a' => 1], $result);
$this->assertAttributeEquals(4, 'count', $obj);

// what to write instead
$this->assertIsArray($result);            // 7.5
$this->assertSame(1, $result['a']);
$this->assertSame(4, $obj->count());      // test the API, not the field

The assertAttribute* family disappearing is the one worth agreeing with: reaching into a private property from a test asserts on the implementation rather than the behaviour, and every one of those tests breaks on a refactor that changed nothing observable. assertArraySubset is genuinely useful and its removal is more annoying — the replacement is usually two explicit assertions, which is more typing and a clearer failure message.