I’ve suspected for a long time that I have caching difficulties. This is exactly what I have seen since yesterday. WordPress without a caching plugin warns me of a problem.
The under-performance warning is removed after installing a caching plug-in. Unfortunately, the tool is incorrect because the performance does not increase.
I’ve been getting a lot of error messages while using the caching plugins. I thought I fixed it, but it’s not.
The error msg on your second screenshot refers to Cloudflare caching of dynamically generated pages (HTML). Cloudflare does not cache HTML by default. You need to use a feature or product for that. What Cloudflare product are you using to cache your pages? APO for WordPress? Cache Rules? Workers?
OK, so you are not using any feature that would have Cloudflare caching your HTML, so default behavior applies. And default behavior is not to cache HTML. Your caching issue is an origin issue, Cloudflare does not cache your pages and does not interfere with origin caching. You need to seek help with the plugin support forum.