This has been detected by MDL-76444 (inspecting apache logs before PHP 8.3 / Moodle 4.4 release). It was called "Problem V" there.

Apparently, it happens when, from the assignment view page, some grading stuff or page is loaded. Here it is the stack trace:

138277:[Fri Mar 08 19:48:40.500500 2024] [php:notice] [pid 4694] [client 172.25.0.14:48840] Debugging: The options argument should not be a context object directly. Please pass an array with a context key instead. in

• line 1449 of /lib/weblib.php: call to debugging()
• line 481 of /mod/assign/classes/output/renderer.php: call to format_string()
• line 495 of /lib/outputrenderers.php: call to mod_assign\\output
  renderer->render_assign_submission_status_compact()
• line 4047 of /mod/assign/locallib.php: call to plugin_renderer_base->render()
• line 651 of /mod/assign/locallib.php: call to assign->view_single_grading_panel()
• line 1432 of /mod/assign/lib.php: call to assign->view()
• line 7690 of /lib/moodlelib.php: call to mod_assign_output_fragment_gradingpanel()
• line 415 of /lib/external/externallib.php: call to component_callback()
• line ? of unknownfile: call to core_external::get_fragment()
• line 253 of /lib/external/classes/external_api.php: call to call_user_func_array()
• line 83 of /lib/ajax/service.php: call to core_external
  external_api::call_external_function()
  , referer: http://webserver63976c3e94796505/behatrun3/mod/assign/view.php?id=110000&rownum=0&action=grader&userid=101002

(it happens 20 times per behat run, estimated)

It has been detected in main (4.4dev) although it may affect to previous (stable) branches too.