Photos from years past have been disappearing from my Macbook. Is this because I deleted photos from my phone?

Are you using iCloud to synchronize you MacBook and the iPhone?

If yes all changes on your iPhone will also effect your MacBook!

Base function of iCloud is to keep all devices on the same level.

What function do you use to sync your devices, if it is not iCloud.

Normally Apple does not delete photos on a whim

Ralf