There can be three issues when it comes to high bounce rates, which are Google Ads, data feed or landing page issues.
Before I explain the potential reasons and what can be done to improve. I have analyzed over 50 accounts and many more public sources which confirm that above 60% bounce rate for Shopping Ads is very normal. This due to the behavior of how customers use Google Shopping. Customers tend to browse through multiple ads, before they choose to buy a product. As Google Shopping is essentially a marketplace / catalogue a customer will click on an ad, and if they are not seeing what they find, go back to the previous page which is Google Shopping and continue to search.
Customer tend to click on ads a lot more in the shopping tab, due to the limited info and small image presented. Take yourself as a prime example, view a shopping ad, how likely are you to click on it, to view more details, while not effectively setting your mind to buy. This mindset with shopping ads is extremely high.
So do not worry about high bounce rate with Google Shopping, everyone has the same experience.
More info on improving the landing page.
Always make small changes and analyze the results. Making too many changes at the same time may result in not knowing what worked. Or never be able to improve your issues.