Hi Susan,
Thanks for your feedback. What you describe sounds like it could be caused by Google Auto ads.
The AdSense “Auto ads” function can place ads automatically on your site. They decide about position, size, and number of ads.
If you enabled Auto ads through Advanced Ads then you can remove their code in Advanced Ads > Settings > AdSense > Verification code & Auto ads.
However, AdSense can also inject Auto Ads through individual ad units. You can only disable that behavior directly in your AdSense account. Go to your AdSense Dashboard > Ads > Overview to do that. There, you can exclude pages or content areas of your site.
You can follow this tutorial and learn how to place AdSense ads manually on your site. This makes sure that AdSense ads will appear on positions of your choice on mobile and desktop.
Please let me know if you need anything else.
Best regards,
Henning