Reported by a customer, that after upgrade to 7.0 their triggers started to not work as expected, because forward slashes were being duplicated in their triggers.

Comparison between 6.4 and 7.0:
Trigger prototype is the same on both instances:

6.4 Trigger and problem:

7.0 Trigger and problem:

When double quotes are removed from the output part of regsub macro function in the trigger prototype, everything works as expected.
Trigger prototype:

7.0 trigger:

7.0 problem:

Omitting output from 6.4 for this because it's the same.

In our documentation nothing is stated about this change, so from our perspective it's either undocumented behaviour, or a bug.
For example, our documentation on regsub macro function has some examples, and based on those examples, having quotes around output part of the regsub macro function shouldn't cause issues like this, but work fine:
https://www.zabbix.com/documentation/7.0/en/manual/config/macros/macro_functions

Here are templates for 6.4 and 7.0 with this test set up:
6.4_template.yaml 7.0_template.yaml