Firstly, i am new here, so if you have any tips on entering bugs!

It may happen in all 3.x versions, i do not know.

I have two Zabbix environments on one system, which i upgraded, one from
3.2 to 3.4.4 and one from 2.4.2 to 3.4.4.
I was unaware of SocketDir for the alerting socket, and the default to create them in /tmp.
I had trouble starting the second environment and found out this socket thing.
I changed the second environment to point SocketDir=<some_where_else>.
Starting zabbix_server in the second environment gave alerts in the first.
So, it looks like the alerting routines are connecting to the default socket in /tmp before the config with SocketDir=<some_where_else> is set.

Steps to reproduce:
Create two seperate Zabbix environments on one system (1 and 2 for reference)
Startup env 1 (This will use /tmp for alerting socket)
In env. 2 put seperate folder for SocketDir in config.
In env. 2 take care of triggering alerts on a regular basis.

Stop env. 2.
Start env. 2

1. Changes in configuration...
2. Navigate to screen title...
3. Click on screen element...
4. ...

Result:
I get alerts from env. 2 in env. 1

Expected:
No Alerts from env. 2 in Env. 1