I was searching patent drawings via google patent search for ideas on how to make something for myself and found another patent that was cited where the patent was granted and then the inventor failed to pay the maintenance fee several years ago.

Is the patented product now in the public domain since the patent holder didnt pay the fees?

Its been a few years since it lapsed according to google :

Information on status: patent discontinuation
PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362

Lapsed due to failure to pay maintenance fee
Effective date: 20201108

Improve it and file a patent improvement then you own it .
Yes it’s in the public domain now.