In practice all of the variables in your Shopify store in constant flux.
Say you manage to bring more traffic, but it isn’t as targeted as before. These new people won’t respond so well to the offers on your store. This will drive conversion rate down.
Are you going to freak out? Probably.
Is there a need to freak out? Not at all.
Despite the decrease in conversions, because of the increased traffic your revenue may stay the same or even get a slight increase. So, before you start worrying, remember to look at the big picture. Evaluate variables in context. Measure revenue against previous periods.