Blocks are slow or impossible to break in creative

So when I normally built, I could break blocks in creative with a single click. But after 1.21, it took about 3 seconds of holding down the break button to break a single block. What's weird is that it breaks blocks below, behind, or wherever I'm facing. I don't know if it's with the update, or all the add-ons in my world (around 8). 

I couldn't get my files to under 10.00 MB so sorry if you don't understand what I mean by this.