You have some tone issues. Let me bring them up.
housing SCP-1346 has been commandeered
'commandeered'.
almost 45 cm thick
Why couldn't we just write 'approximately' or '44.8 cm thick'?
An identical door sits closed
Doors don't sit. This of course is my opinion here, so this particular one may be iffy.
The passageway itself is a seamless, cement corridor having no other doors, windows or alcoves.
I don't think you need 'seamless' in here. It's not only iffy tone, but it's redundant with 'having no other doors, windows or alcoves'.
unshielded electronics
Whattya mean 'unshielded'. How does one shield the electronic against random fear?
Around this time, subjects start to report feelings
I use 'around this time' when writing histories for roleplay characters. For SCPs, I usually write 'during this time' instead. It sounds less vague-y.
dislike the subject harbors
'harbors'.
These behaviors are more likely to manifest the more often a person is exposed.
What behaviors are we talking about here? Are we talking about the 'heh, whatever' behavior, or the 'NOPE NOPE IT NEVER HAPPENED LA LA LA NOT HEARING YOU' behavior?
continues to be generated unabated even when power to the subbasement is severed
'unabated' and 'severed'.
Finches tend to avoid approaching the zone.
'tend to' is unnecessary here. You get the same results saying 'Finches avoid approaching'.
detected heavy, rhythmic thumps, like footsteps, moving beyond the door
Look, you can just say 'detected sound similar to footsteps moving beyond the door'. All this commaspam just makes it stupidly wordy.
Overall, I like it! Nice job, dude.