Is this a problem ?

Hello. I have a tech blog and until now I used to rank some easy low competition keywords with no backlinks. I managed to rank them on 2nd and 3rd page on google. But for a month now I noticed that I couldn't do that anymore. Google now ranks me on 13th 14th page for the same competition level keywords. Could this be a penalty? I mention that my other keywords keep their good and stable SERPS.

Thank you!

Every keyword is different, this is not a penalty because your other keywords did not drop.

A penalty is always applied to complete domain. so that make no sense of a penalty if you have some keywords ranking good and some are not.

all keyword are fdeficults but also depend on the person