No. An actual issue (or not) is not even there.
It is somewhere in loading image resource into ImageList.
I can reproduce the issue only by following:
1. Create Application project
2. Drop ImageList on the Form
3. Load a picture into ImageList
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It looks like it is a false positive of Valgrind.
If variable Signature is
local it shows mem error "Conditional jump or move depends on uninitialised value(s)".
file imglist.inc
procedure TCustomImageListResolution.ReadData(AStream: TStream);
var
Signature: TImageListSignature;
...
Valgrind is happy as soon as Signature is moved outside of the procedure.
So it does not like arrays in stack. But is Ok with same arrays in heap.
In simple program test it also depends on a size of array.
16,32 are ok, but 1,2,4,8 show the error.