You've observed a real effect! It's not a "reset penalty" in a punitive sense, but rather an "optimization disruption" for automated campaigns when you pause and restart them.
Here's why performance (impressions, sales) drops:
Learning Phase Reset: Automated campaigns use machine learning to constantly optimize. Pausing, especially for longer periods, essentially tells the algorithm to "forget" what it learned. When restarted, it re-enters or extends a "learning phase," during which performance is unstable and often less efficient until it gathers enough new data (e.g., 50 conversions in 7 days).
Lost Momentum: Campaigns thrive on consistent data flow. When you pause, you stop feeding the algorithm fresh signals. It loses its "rhythm" and ability to make real-time, efficient decisions.
Dynamic Market Changes: The ad auction doesn't pause. Competitors continue to optimize, and audience behavior or market conditions can shift. When you re-enter, the landscape might be different, making it harder or more expensive to achieve previous results.
In short: Pausing breaks the algorithm's learning and adaptability. It's like turning off a finely tuned engine – it needs time to warm up and re-optimize when you restart, even if everything else is the same.
Instead of pausing, consider:
This keeps the campaign active and the learning signals flowing, minimizing disruption.