Do you think I need a new 12v battery?

2016 Prius, purchased in August of that year. About 51,000 miles on it now. Before the pandemic hit, the longest it had gone without being driven was 10 days.

Like many people I started working from home recently, and my Prius sat not being driven for 25 days. Then I tried to start it up to go grocery shopping, the display briefly showed some warning about shifting to park (???) then nothing. The display went dark and the car wouldn't start. There was just a very quiet ticking noise that seemed to be coming from under the hood. I jump-started the car with another vehicle and drove around the block. A couple hours later I did my shopping trip. Everything seemed to be fine...

Until another week of no driving went by and it wouldn't start again. This time I used one of those portable car battery chargers. Drove around for about half an hour right after, which is what I've read your supposed to do. That was four days ago, and in that time I've been starting it once per day, trying to figure out how long it takes the battery to discharge. So far it's started up perfectly every time.

Additionally, I took my Prius to the dealership for regular maintenance about two months ago (before the current trouble started) and they didn't mention anything being amiss with the battery.

So what do you think? Is my 3.5-year-old battery bad and in need of a replacement, or did it just need that recharge, and to not be left sitting for three weeks? If I can avoid spending a bunch of money on a new battery, I'd rather not, but I'm willing to do that if it's necessary.

Any advice from people who know more about car maintainence than me (an car-illiterate moron) would be greatly appreciated.