yellow oil pressure warning light gone off without doing nothing but then I ran 1000km and found low oil level

some weeks ago I saw a yellow oil pressure warning symbol and I move the dipstick up and down then it gone off. As I am not a Car guy I didn’t check the oil level because I don’t know how much it should be.

One week After that I gone for long trip around 1000km in 3 days (500km each side) but have not observed anything at that time.

One week after that I again saw the same warning in yellow and did the same by moving dipstick and it gone off.

Now today I saw again and visited the service station and they found oil level is at the lower level on the dipstick mark and they topped up 1 liter oil.

My question is, I have drove many long trips during the time like 500km continuous so, what could be the possible damaged to the engine because of my ignorance ? And how to check it through any sound or any performance ?

My car is : VW Polo 2011 1.2 TSI (1,30,000 km as on today)

Thank you very much in advance.