Why have I been getting very limited hours at my job?

I’ve been working at a grocery store in my area for almost 2 years, I’m a pretty dedicated employee but for some reason my hours have drastically decreased. I used to work full 8 hour shifts about 3-6 ish days a week. Now I’m literally getting 1 shift a week that’s only 4 hours long. This has been happening for multiple weeks, and for the next weeks on my upcoming schedule it’s the same thing. I’ve been applying to other places to hopefully find a new job, but why would my hours be drastically cut from 20-30 ish hours a week to never more than literally 4 hours a week?
Why have I been getting very limited hours at my job?
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