I’m new to archery and have my bow set to 40 pounds. It’s shooting well at 30 yards, but when I crank up the poundage to 45 pounds, it starts shooting way left. What is my issue?

There are actually quite a few things that could be affecting the arrow in this situation. One thing to definitely consider, since this is a "new archer", is the increase in draw weight. Increasing the draw weight, especially in new shooters, can cause a variety of form issues from not getting into the anchor points properly to torquing the bow at full draw. Always make sure you're 100% comfortable at your current draw weight before increasing the poundage. Another thing to consider is the arrow's spine. Double-check on a spine chart to make sure those arrows are not too weak for the draw length and increased draw weight. And if possible, go to a local archery shop and explain to them the issue that you're having. Someone with enough experience should be able to help you out with the issue.