Not possible to escape parentheses inside RegEx for function 'count'

Let's say the value of metric is:

(0) hello

If we want to detect this 1:1 using regex, we will use:

^\(0\) heelo$

For version 6.0.8 it works fine in trigger function:

But when upgrading frontend to 6.0.9 and modifying trigger expression a little, it prints:

Cannot update trigger
Invalid parameter "/1/expression": incorrect expression starting from "count(/host/input,#2,"eq","^\(0\) hello 123$")=1".