Why is my switch is charging slowly?

ok so i left my switch in an area of my room without it being plugged it (which i have done before). it was maybe 2 months(ish) before i picked it up again (mainly due to school).

last time i used my switch was early april, and it had no issues with its charging then.

i went to charge it last night and when i went to check on it this morning (maybe 8am), it still had no battery? so i unplugged the charger block & replugged it back in.

i check around 12pm to see what percentage it was at, and it was at 19%. currently, it is at 25%.

why is it charging so slowly? its never done this before, and ive had this switch for 5 years. ive also never changed out the charger: ive had the same, official nintendo switch charger since i got it originally. is this an age-related issue? do i need a new charger?