Upgrading AdvStringGrid : goFixedHorzLine keeps getting added to Options

I'm currently upgrading our components packs, and Delphi version (10.3 to 11.3).
The AdvStringgrids (our local descendant) are going from version to

When I open a file with a .dfm in the IDE and save without any modifications, a few properties are changed.
The most visible to me is goFixedHorzLine getting added to the Options property. The others are some Color/ColorTo and some Fonts.
They even come back if I change in the "Object Inspector", save, verify with GitKraken that the change is here, close the IDE, reopen the project and then the file, I can see that the horizontal fixed lines are back.
I save, and see goFixedHorzLine come back.

I tried, in the local descendant, to redefine the default for the property.

  DEFAUT_OPTIONS =  [goFixedVertLine, ....

    property Options default DEFAUT_OPTIONS;
constructor TLocalGrid.Create(AOwner:TComponent);
  Options := DEFAUT_OPTIONS;

Rebuilt our whole component suite (because of dependancies) with .bat and Delphi closed.
And the problem still persists.

I tried on a simple Vcl.TStringGrid created in D10 and didn't see this behavior when opened in D11.

What can I do to stop that behavior ?

I cannot reproduce this.
When I open this project, goFixedHorzLine is never set.
Project1.zip (5.4 KB)

Thanks for checking.
I still see the same thing with this project.
Must be something else in our code that cause this. I will continue my investigation.

I confirm that when using the unaltered sources for VCL UI Pack, I don't have this problem.
I will analyse all the differences to see if I can find the culprit.

Update on the investigation :
I've located the + [goFixedHorzLine] that is causing this, but it's not one of our modifications.
It's in TAdvStringGrid.InitVCLStyle.InitColors

But, as I said, it's not something we modified, and we didn't change any InitVCLStyle call.

I will continue to search what is triggering this, with someone to help me next week.

Is AdvStringGrid.UIStyle different from the default value tsCustom?

No, UIStyle is set to tsCustom on all our AdvStringGrid
(confirmed with a search)

Then I cannot see why it enters InitColors
Please provide a sample source app with which we can reproduce the problem here.

Thanks for your help.
I will be trying to do that next week.