Why HFD key work in FD and via versa, it was NOT like this from Saint Patrick day to Eastern day?

The problem is as title. I sense a market potential to do the labor work for future 2x drop by collecting Iron key (HIH) and cath keys (HFD) and sell it when 2x event come (Eastern), hoping to get my lvl 900 weapon faster than collecting shopfood. Before I do this, I double check if the key with same name only work in Herotic but not regular. Somehow after 2x event over, People were saying regular FD key work in Herotic and frame me for selling 170 HFD keys (during 2x event) was from regular FD. I did a quick test —> (2022/04/25) HFD cath key work for FD and via versa, but HIH and IH can not across each other with iron key.
Now, you can track my account activity to see how many times i enter FD and HFD cave to verify my status.
My assumption as an outsider is that —> In order to fix the crash issue, does old version of patch was check out to fix the crash issue, and the old patch's bug also carry to current? because HIH and IH is still a fixed, the time line cause my speculation.

sadly, I already farm 100 more keys from HFD, i hope you can verify my key content.

Thank you.