Ooof.... updated my ddev env to PHP 8.2:
haraldei@stigmata% ddev phpunit
PHPUnit 10.5.20 by Sebastian Bergmann and contributors.
Runtime: PHP 8.2.24
Configuration: /var/www/html/core/tests/phpunit.xml
DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD..........DDDDDD....DDDDDDDDD 63 / 269 ( 23%)
DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD..DDDDD 126 / 269 ( 46%)
DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD 189 / 269 ( 70%)
DDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD 252 / 269 ( 93%)
DDDDDDDDDDDD..... 269 / 269 (100%)
Time: 00:11.239, Memory: 14.00 MB
OK, but there were issues!
Tests: 269, Assertions: 513, Deprecations: 37.
Luckily it seems most of these deprecations have the same root cause, thought, so should be easy to fix :)