Got Surgery And Was Given A Warning Email From My Job.

Location: California

I let my HR know ahead of time that I needed Saturday and monday off. It was Friday when I told them I needed it off. I was working Friday and felt a lot of pain in my body and it affected my ability to work well. So I let them know I wouldn't be able to continue because I was in so much pain. I left home early then emailed my HR about the situation and that I needed my next two work days off.

Saturday's a good day, no warning, it was a cancelled shift that day and I got my Doctor's note and emailed it to HR. I noticed monday wasn't cancelled. I asked for Monday off on Friday because I really was in that much pain and my job would make me feel so much worse while working. I asked my Doctor if I should go to work in my current state on Monday. He told me no and to come back on Monday. He gave me an extension to not go to work. From Sat through Mon. I then email that note to HR that same day, Saturday. My Monday shift was then cancelled on Saturday.

Monday comes along, I go to my Doctor, he tells me the bad news that I barely found out that today that I needed to go get a surgery. I go and get it done. I get home and look at my email to see a warning given to me by my job for missing today. The reason being a last minute call out. I'm wondering why I didn't get that same warning for Saturday? I did ask for Monday off ahead of time on Friday. They had no issue giving me Saturday off when I asked for it off on Friday. But apparently not for Monday. Maybe that could still be considered a last minute callout but I should've gotten that warning for Saturday if they considered me asking for my Monday shift to be cancelled AGAIN, 2 days before Monday I said I'd give a note. I feel like its incredibly scummy because I got a surgery. They really didn't know, but I didn't either.

Note: I forgot to add I did barely start working here. I started on the 18th of May.

My question is if jobs are legally allowed to give me a warning on a day I needed off for getting surgery, when I let them know ahead of time I needed the day off even though I didn't know I'd get surgery?