AN515-55-53ES i noticed that it would stop charging occasionally

Update: Exact model is AN515-55-53ES

Can you tell me which indicator flashes orange light? (Charging or power indicator?)

https://community.acer.com/en/discussion/comment/1264972#Comment_1264972

Hi, sorry it's the charging indicator.

Try to unplug both the battery and the charger, and press and hold the power button for 10 seconds for power reset.

If that doesn't work, try to use the laptop without the battery, does the charging indicator still blink?

https://community.acer.com/en/discussion/comment/1264976#Comment_1264976

Hi, thank you for your reply. I've tried a power reset already (should have said that, my bad), and without any battery, no lights appear at all + the laptop doesn't turn on.

Does the battery symbol in Windows change to charging when the charger is plugged in?

https://community.acer.com/en/discussion/comment/1264980#Comment_1264980

yes, it will stay charging for a while (at the moment it's at 23%) then it'll start flashing and begin to drain.
To clarify from before, it's actually BOTH the charging and power light which flash. I don't know if I somehow didn't notice that earlier, or if it's changed, most likely just focusing on the charging light I think.

As you mentioned that you have bought a new charger, does the new charger have the same wattage as the old one?

https://community.acer.com/en/discussion/comment/1264983#Comment_1264983

the older charger (which is not the original, but has worked for over a year);
Input: AC100-240V 2A 50-60Hz
Output: 19V - 7.1A 135W

The newer charger;
Input:100-240V 1.8A 50-60Hz
Output: 19V - 7.1A 135W

I searched for a charger for the type of laptop it was; it was the closest one I found on amazon from a quick look. Is the discrepancy in the Input enough to be an issue?

The charger output is fine so it is not the charger issue for now. If those above suggestions don't work for you, you can take the laptop to a PC repair shop that specializes in motherboard repair, as this can be related to charging IC/Mosfet faulty.