Random ass experience i had one night in 2021

Now, I know this seems like fiction, but I promise this is real. So one night around Christmas in 2021, I was watching SCP videos on my phone at like, midnight and I got up to use the bathroom and I see this thing at the top of my staircase. (floor plan below) 

So I'm scared shitless because this thing looked like a shadow but not because the bathroom light was on, and it kinda looked like an alternate from the Mandela catalogue but whatever, I run into my bathroom and use it and when I w alk out, it's not there anymore! Like what the fuck was that??? Was it a hallucination??? Was it a dream??? Was it a cryptid??? We'll never know! I don't know what the fuck happened but yeah, it freaked me the hell out and I didn't use the bathroom at night for months.