my macbook air 2020 laptop stop charging , i left it alone for 1 week shut off and unplug and now its fully charged

Its not really a problem but i was wondering if anyone else faced this issue. So i can try to understand why this might have happend. I was having a meeting and when i hang up my battery was at 20%. I tried charging it but the battery wouldn't charge. I tried different outlets and chargers and no luck until i eventually gave up and by then it was at 5%. For a bit more background 3 months ago my graphics card needed to be replaced which we did at apple. Anyways I left it unplug at 5% i never charged it again since then. And by mere luck I open it again today one week later and the battery was at 98%. Even tho i never charged it. Moreover once i plug the charger it was charging once more. I guess my concerned is if anyone has experience anything like this. And even tho on my battery setting says the battery is normal. What are the odds this issue will happen again. Thank you