Please explain this light leak problem with old blend files opened in 4.0

[thinsoldier]

I opened an old file and had a crazy light leak problem.
I rebuilt the geometry from scratch to be exactly like the original geometry and now there is no problem. I don’t understand what’s happening.

B4.0 light leak problem hot living.blend (282.7 KB)

[oo_1942 (Kim)]

There is something missing in the setting.

[thinsoldier]

Thank you. That was driving me crazy.