Backed up my phone through my mac and now everything from the past year is deleted! My phone is how it was last summer: photos, wallpaper?

I plugged my iphone into my laptop (mac), it asked if I wanted to back up my phone so I did, now my phone is exactly how it was a year ago. It's my old wallpaper, my old apps, and when I go into photos the most recent photo is from 2018. Everything from the past year is gone.

Added (1). Is there any way to reverse what I've just done? This is absolutely horrible, all my pictures from the past year have disappeared, all my notes with important passwords, everything.

Uh, huh.

The backup went the wrong way.

Don't do ANYTHING that could overwrite the old data --- no downloads, no viewing of texts, etc.

Try an "undo", but don't expect much.

This is why you Have to be Extremely careful and either Never back up one device with another
or Frequently sync them (but be careful about which one is the "master"!).

Before you do anything else, try to find someone who can help you in person,
and that does Not mean someone who only Says they know what to do ---
get Proof of their knowledge First before you allow an attempt at solving your problem.

That's what happens when you don't read the messages the Mac was giving you before you confirmed a full restore to an old backup. It is what it is. You live and you learn.

The short answer is that you didn't pay proper attention to the feedback and instructions you were given by the Mac when you were stumbling through the back up procedure. Pay more attention from now on.