[Inconsistent]: Upgraded Fleet Server 8.18.0 BC3>9.0.0 BC3 goes offline permanently on upgraded self-managed kibana.

**Kibana Build details:**
```
VERSION: 9.0.0-beta1 BC3
BUILD: 83575
COMMIT: a9ae718019d3909912f81e5d388ef597929071a1
```
Artifact: https://staging.elastic.co/8.18.0-16a1508a/downloads/beats/elastic-agent/elastic-agent-8.18.0-windows-x86_64.zip

**Preconditions:**
1. 8.18.0 BC3 Upgraded to 9.0.0 beta1 BC3 Kibana self-managed environment should be available.
2. 8.18.0 BC3 Fleet Server should be installed on 8.18.0 BC3.

**Steps to reproduce:**
1. Upgrade the 8.18.0 self-managed kibana to 9.0.0-beta1.
2. Upgrade 8.18.0 fleet server to latest 9.0.0-beta1.
3. Observe Fleet Server upgrades successfully and then goes permanently offline on upgrade.

**Expected Result:**
Upgraded Fleet Server 8.18.0 BC3>9.0.0 BC3 should remain Health on upgraded self-managed kibana.

**NOTE:**
- When we reinstalled the 8.18.0 Fleet server on upgraded self-managed 9.0.0, it upgraded successfully.
- The issue is only observed when it was installed on 8.18.0 BC3 build.
- [Update]: The issue is not consistently reproducible.

**Logs:**
[elastic-agent-diagnostics-2025-02-14T10-02-11Z-00.zip](https://github.com/user-attachments/files/18797275/elastic-agent-diagnostics-2025-02-14T10-02-11Z-00.zip)

**Agent json:**
[EC2AMAZ-ED5G7SB-agent-details.zip](https://github.com/user-attachments/files/18797278/EC2AMAZ-ED5G7SB-agent-details.zip)

**Screenshot:**