Why is my new MacBook Air M4 battery draining so fast?

...usually one YouTube tab, and a few GDrive tabs for work

Watching any videos is a high-demand task and, in general, any connection to Google tends to be rather piggish. Even having this open in the background can tax the battery.

If you were wrongly advised to install anti-virus software or so-called "cleaning" apps, those will increase battery load. Running an external monitor will as well.

These things are hard to fully diagnose in any text-based setting, but we can get close. If you want a data-driven evaluation in this setting where we can neither see nor touch your computer, please post an EtreCheck report. We can quickly and within the limitations of these forums help you determine what issues are at play without our playing a protracted game of "20 Questions" with you that could go on for days. 

EtreCheck Pro is available here:

https://etrecheck.com/index

The free version will do nicely for this purpose, although the app is worthy of our financial support.

We can see hard data about app demands, drive performance, software issues and interferences, and RAM usage. Etrecheck is the development of a long-serving and trusted ASC contributor. It is a reporting app, not a "fix-it” app, expressly for displaying information in these forums to help us help you remotely. It will not reveal any personal or secure information.

Please see this excellent user tip on how to post long text reports like EtreCheck's into a forum response:

How to use the Add Text Feature When Post… - Apple Community

Please post the entire report. What seems insignificant to a new Etrecheck user can hold answers for those of us who have reviewed thousands of those reports.  Etrecheck scrubs any personal info if you follow the posting steps in the above article.

Otherwise, I recommend you have Apple evaluate.

Have you tried to restart the Mac to see if the issues persist? Have you tried to boot the Mac in the safe mode to see if the issues persist? If the issues dont persist in the safe mode, they are caused by an external piece of software, you might want to evaluate the external software installed to your Mac

Start up your Mac with Apple silicon in safe mode

1. On your Mac, choose Apple menu  > Shut Down.
2. Wait for your Mac to shut down completely. A Mac is completely shut down when the screen is black and any lights (including in the Touch Bar) are off.
3. Press and hold the power button on your Mac until “Loading startup options” appears.
4. Select a volume.
5. Press and hold the Shift key, then click Continue in Safe Mode.
6. The computer restarts automatically. When the login window appears, you should see “Safe Boot” in the menu bar.