Reproduce:
Observe: the notice "[FLOW] apiRequest already in progress loadMoreTopics" appears multiple times as you scroll up.
This is intentional I think. Well, the part about doing infinite scroll despite you going upwards.
When you e.g. 1-50 loaded, then click on #200, it doesn't load 51 through 200. It loads a range near 200, then gaps are left for the rest. As you scroll upwards, it fills in the gaps. This was one of the complex parts to get working originally.
Yeah, I think you're describing the intended behavior. Let me know if I'm misunderstanding the bug report, or if you want to check in about the ToC's "gap handling".