Multi instance Task Manager issues after 8.15

[tttttx2]

Kibana version:
8.15+

Elasticsearch version:
8.15+

Server OS version:
Docker on Debian

Browser version:
N/A

Browser OS version:
N/A

Original install method (e.g. download page, yum, from source, etc.):
Docker

Describe the bug:
I have seen multiple clusters that are throwing Taskmanager errors (Degraded, even though not overloaded at all, and HealthStatus.Error because of expired hot timestamps). Furthermore, they only show a single 'observed_kibana_instances' on api/task_manager/_health API Endpoints. However, on Stack Monitoring all kibana instances are shown.

I guess something is regularly killing my task managers on multiple instances, and somehow they don't appear to 'talk' to each other.

I haven't observed this before 8.15, and a cluster on 8.14 is still working fine (with pretty much identical config)

Steps to reproduce:

1. upgrade past 8.15
2. Have multiple kibana instances
3. setup kibana for load balancing, still only 1 observed in health api

Expected behavior:

Multiple kibana instances should be shown on the health api, and task manager should not be regularly degraded (once every 1-2 minutesor so)

Screenshots (if relevant):

Errors in browser console (if relevant):

Provide logs and/or server output (if relevant):

Any additional context: