date->diff error php 8.1

Trying to figure out why my sessions were expiring immediatly on php 8.1 but not 8.0, I found the following:
code fragment:
    $foo = new DateTime();
    $bar = new DateTime($_SESSION['ts']);
    var_dump($foo);
    var_dump($bar);
    $diff = $foo->diff($bar, true);
    var_dump ($diff);

php 8.0:
object(DateTime)#2 (3) {
  ["date"]=>
  string(26) "2022-06-07 18:33:01.543434"
  ["timezone_type"]=>
  int(3)
  ["timezone"]=>
  string(10) "US/Eastern"
}
object(DateTime)#3 (3) {
  ["date"]=>
  string(26) "2022-06-07 18:32:58.651232"
  ["timezone_type"]=>
  int(1)
  ["timezone"]=>
  string(6) "-04:00"
}
object(DateInterval)#4 (16) {
  ["y"]=>
  int(0)
  ["m"]=>
  int(0)
  ["d"]=>
  int(0)
  ["h"]=>
  int(0)
  ["i"]=>
  int(0)
  ["s"]=>
  int(2)
  ["f"]=>
  float(0.89220200000000005)
  ["weekday"]=>
  int(0)
  ["weekday_behavior"]=>
  int(0)
  ["first_last_day_of"]=>
  int(0)
  ["invert"]=>
  int(0)
  ["days"]=>
  int(0)
  ["special_type"]=>
  int(0)
  ["special_amount"]=>
  int(0)
  ["have_weekday_relative"]=>
  int(0)
  ["have_special_relative"]=>
  int(0)
}

php 8.1:
object(DateTime)#2 (3) {
  ["date"]=>
  string(26) "2022-06-07 18:31:30.428703"
  ["timezone_type"]=>
  int(3)
  ["timezone"]=>
  string(10) "US/Eastern"
}
object(DateTime)#3 (3) {
  ["date"]=>
  string(26) "2022-06-07 18:31:27.274847"
  ["timezone_type"]=>
  int(1)
  ["timezone"]=>
  string(6) "-04:00"
}
object(DateInterval)#4 (16) {
  ["y"]=>
  int(-1)
  ["m"]=>
  int(11)
  ["d"]=>
  int(29)
  ["h"]=>
  int(23)
  ["i"]=>
  int(0)
  ["s"]=>
  int(3)
  ["f"]=>
  float(0.15385599999999999)
  ["weekday"]=>
  int(0)
  ["weekday_behavior"]=>
  int(0)
  ["first_last_day_of"]=>
  int(0)
  ["invert"]=>
  int(0)
  ["days"]=>
  int(0)
  ["special_type"]=>
  int(0)
  ["special_amount"]=>
  int(0)
  ["have_weekday_relative"]=>
  int(0)
  ["have_special_relative"]=>
  int(0)
}

What is happening here? Am I doing something wrong that just happened to accidentally work from 5.6-8.0, or did I find a bug?


JAB