Why Do My Indoor Herbs Get Leggy Even on a Sunny Windowsill?

A bright room can still leave herbs short of light. Look at new stem spacing, actual sun at leaf level, and neighboring foliage before pruning or feeding.
The Best Herbs to Grow Indoors When You Have Almost No Space

If your kitchen has one decent windowsill and not much else, you can still grow useful herbs indoors. The trick is choosing plants that earn their square inches with repeat harvests, compact growth, and realistic care.