I must have been blind 😅
And I mean, even worse than that, because I also searched the settings menu for "Drag", and I swear I didn't see it. Now, I couldn't miss it of course.

@guigirl said:

If you already knew how to disable it

Well, I managed to turn tab stacks on/off, but I never before found the exact setting @Ayespy mentioned.
I could re-enable tab-stacks any time, I just didn't want to, as that turned drag and drop back on - which is the setting I didn't see.

Anyways, thank you guys. Can the question be marked as solved?

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