Do I have to apply sunscreen even indoors?

I had 3 IPL sessions, and the director advised me to apply sunscreen, foundation, etc. when going out.

For a long time, applying basic skincare followed by sunscreen has been essential for me in the morning, and I only apply basic skincare at night.

When going out, I almost always do basic skincare -> sunscreen + powder.

Sometimes I go out after just applying sunscreen.

I'm wondering, if I don't go out and stay indoors, do I not need to apply sunscreen?

Lately, double cleansing in the evening has become a bit of a hassle.

I only wash my face with soap in the morning.

For dinner, I do oil followed by soap.

This is the sunscreen I use.