append-option in capture not working with included templates anymore

We're running a complex structure of template includes and there we use {capture} with "assign".
To keep the array in the scope of the parent template we pre-defined the variable on top of the template that includes the other templates.
That worked so far with v4.5.3, but not anymore with v5.4.0+. I think also it never worked in v5 as the file was not changed since creation.

As I saw in v.4.5.3 there was some code for scope handling in the append() function - but that's not there anymore in v5.4.
For testing I added the global scope to the $this->assign() in src/Data.php:189 and it worked again.

Also with a little bit more debugging the already existing value from the main template gets fetched and the new capture-append-content is added but it's saved with SCOPE_LOCAL (as default) and so there is added a new variable for the included template.

Inspect src/Data.php around line 189 and the append() and assign() paths, starting with how included templates resolve scope. Reproduce the v4.5.3 versus v5.4.0 behavior with a parent template, included templates, and capture append; done means the appended value remains in the parent template's predefined variable rather than creating a local variable.