As of July 2022, GA4 bounce rate does exist. But it's a very different metric from UA. Let's compare the two bounce rate metrics.
Google Analytics 4 Bounce Rate (GA4)
A Guide to Bounce Rate in Google Analytics GA4
GA4 vs Universal Analytics
GA4 Setup Tutorial: Install and Configure in 10 Steps
The Complete Comparison between Universal Analytics and Google
GA4 vs Universal Analytics: The Key Differences
Bounce Rate in GA4: Understanding & Using the Metric
GA4 Setup Tutorial: Install and Configure in 10 Steps
Universal Analytics vs. GA4 [Complete Guide]
Q&A: GA4 vs. Universal Analytics - JB Media Group
Image Alt Tag SEO Generating and Using Alt Text for SEO Results
GA4 vs UA: 8 Key Differences Explained - Kick Point Playbook
UA vs GA4: How eCommerce Development Agency Migrate?