Hesitating to start on the very first start of the day?

My car has a new battery (bought 5 months ago) and a little over a month ago my car started hesitating to start on the very first start of the day. It's a push to start, so when I press the button, it hesitates for 2-3 seconds, which you audibly hear. Then starts/runs fine the rest of the day.
(Example: I start my car at 8am- it'll hesitate to start, but then runs fine. Let's say I then drive 5 min up the road, turn off the car & it then sits for 8 hours. When I go back out to start my car. Zero hesitation. It starts perfectly) It's only the very first start of every day.

My car recently sat for a week undriven (I was sick and didn't leave the house) My car was completely dead (no lights/ power at all) when I tried to start it. I had to get it jumped for it to even start. I would assume something is draining the battery while it's parked?

I've been going out to start my car daily, even if I'm not going anywhere just so it won't shut off on me again until I get this figured out.

The battery is under warranty, but they've tested it twice and say it's good. The alternator also tested with the correct voltage. The car is fine once it's started and going. However, once it sits overnight or longer, is when the hesitation happens when starting.

Is it worth it for me to take it somewhere & pay for a diagnostic test? What if they can't find anything wrong since it's fine once the car starts for the day?

(I also do not have anything plugged into my car, aside from my phone charger, that could be draining the battery when it sits)

What could this be?