Possible reasons for worse battery life?

Firstly, I apologize if it annoys you to read about battery-related issues with this phone. However, I just wanted to confirm this, perhaps find someone with a similar experience.

I recently bought a Galaxy Fit3 and have had it paired with my S23 constantly for a week now. My battery life is noticeably worse than before, and I want to confirm the watch is the reason. They are paired via Bluetooth, but I cannot imagine why the phone's battery drains so much faster. I understand the phone sends weather details and synchronizes with the Health app, including daily steps, etc. I just didn't expect it to be this battery-intensive. Standby is noticeably worse. With the screen and AOD off, the phone drains about 5% in 30 minutes.

Now I have to charge my phone two to three times a day when using mobile data.

Do you have any suggestions to minimize phone battery drainage? I don't mind the watch having worse battery life, but I mind it affecting my S23.

Many thanks! Have a wonderful day.