Renaming symbol in chart item properties is reset after you moved out from the widget

[DelazJ]

What is the bug or the crash?

1. In a print layout, add a chart item
2. (Optional I think) In data source, add and configure series. You can even rename them to know what they do.
3. press "Modify chart properties"
4. Under "Symbols list", you can add more symbols, and double-clicking the "Symbol" text, rename it/them.
5. Leave the widget and go back to "Modify chart properties": your names are reverted to "Symbol".

Steps to reproduce the issue

See above

Versions

QGIS 3.99 2e07d98 on Windows 10

Supported QGIS version

• I'm running a supported QGIS version according to the roadmap.

New profile

• I tried with a new QGIS profile

Additional context

Afaiu, symbols are assigned to series in the order they are listed in the widget (1st series take first symbol and so on). I think symbols should automatically take name of the corresponding series, making things clear.
And considering ability to reorder series (#63459), there might be some more thoughts whether the name should be reassigned when moved, or it is assigned at creation time (knowing that you can create symbols before/without series 🤔 )