Where are you located? Arugula is heat sensitive like many mustard family and will bolt even more easily than lettuce. My arugula has been in flower for a while now and I'm waiting to harvest seeds.
This is just one of my salad "garden"
Tallest with cream-colored flowers are arugula
Once this process starts, there's no stopping it, and as senescence sets in, the shape, texture, and flavor will change -- typically more "green" bitter and less mild, nutty, etc.
Most of my lettuce are starting to bolt except the most recently started ones in somewhat shady locations - elongate like your arugula has - and initially I cut them shorter to harvest new shoots, but I'm ready to give up on them soon -- probably by next week. I'm planting what s likely the last of the arugula and lettuce starts this week, and that will be it until late summer/early fall when I can start fall crop of the cooler temp leafy greens.