Question) Is this true? Do I really need to apply sunscreen even when I stay indoors or on cloudy days?

Hello. I have recently become interested in skincare and plan to start taking proper care of my basics. Everyone agrees that sun protection is the absolute foundation of skincare. However, since I spend most of my time indoors, such as at home or in the office, and the weather is often cloudy when I go out on weekends, I am wondering if I really need to apply sunscreen every time. That is why I am writing this post to ask.

I read somewhere that while UVB, which causes sunburn, is blocked by windows or clouds, UVA, which causes skin aging and pigmentation, has a longer wavelength and penetrates not only clouds on cloudy days but also the windows of ordinary houses and offices. I read that even if your skin doesn't look sunburned immediately, exposure to UV rays indoors or on cloudy days can unknowingly destroy collagen and worsen dark circles or blemishes.

Is this really scientifically accurate? I am curious if everyone makes sure to apply sunscreen with a PA rating every day, even on days when they stay indoors or on cloudy days when the sun isn't shining. I would also appreciate it if you could recommend some lightweight sunscreen formulas suitable for indoor use!