For me it's the Asiatic garden beetles. They hide in the soil during the day and then come out at night for an all-you-can-eat coneflower petal buffet.

Mine are being eaten a lot this year too. It's been hot and dry for a long time and the grasshoppers are everywhere.... they seem to be what's eating mine.

Thank you Lindsay Vollmar and party_music50! I haven't spotted anything in action yet, but I'll keep an eye out...

If you don't find the pest in the daytime, go out after dark with a flashlight and look. Many times it can be something you'll miss - that only appears at night.

Could also be gold finches. This time of year when the earlier coneflowers have seeds that are ripe... I get goldfinches going to the not-ripe blooms and pull the petals off. Yours looks odd since the petals are straight line cut off... like scissors and not more random chew marks from bugs.

I agree, nevermore44, I don’t know what type of bug that might be, because there are no small holes, just cut straight off!

I've seen the beetles at night eating the developing petals, so that when they fully open it looks like they've been cut off with scissors.

Update...I’ve spotted these guys all over them, and I believe they are sunflower moths (well, they will be soon). I used BT (that seems like a good product?), so hopefully that works. Thanks everyone for your help!