Your campaign may be more likely to have performance fluctuations when its budget is limited. This is because Google Ads works to ensure your campaigns do not exceed their daily and monthly spending limits, which can cause decreases in spend and serving when close to these limits.
What you can do
Consider increasing your budget to make sure your campaign has enough budget to be able to serve throughout the day.
Need something else?
Check other common reasons why your campaign performance is fluctuating.