I need some more experienced eyes on this but they have made the support premium only and i do not want to buy it right now in the testing phase. I hope someone here can point me in the right direction what happened and how can i make sure it never never happens again.

My Setup (across 4–5 WordPress sites i have used this Plugin with Cloudflare):
Disabled Elementor's own caching
No other caching plugins installed
Connected Cloudflare via API token and added everything they wanted in their documentation
Enabled Cloudflare CDN + caching
Left CSS/JS defer & minification OFF (Premium feature), and HTML minify OFF (testing phase)
Google Fonts optimizations: skipped (Elementor handles them)
"Auto Prefetch On Hover": ON
"Enable Disk Page Cache": ON (default)
Auto-updates in general for WordPress enabled for plugins/core/theme of course

What Happened:
Days 1–2: Everything worked flawlessly, it felt like cloudflare and this plugin worked good together and made my clients with a slower all-inkl hosting a lot faster and cloudflare handled all the delivering.

Day ~3–4: Client reported the site is broken
Solution: Manually purged cache → everything back to normal

Content has been static for months, no updates pushed during this period, i would know it was just a couple days

What I Can't Figure Out:
Why would cached pages break after a few days with no changes? Did cloudflare say this cache expired without any changes and decided to send broken stuff to the visitors? Why did it not load the cache new every 24 hours of 48 hours if something can expire?
How does Super Page Cache + Cloudflare actually work under the hood? Am I misunderstanding the caching flow?

What's the correct workflow to set this up once and never worry again? I need to be able to ignore these sites for weeks/months and know everything stays healthy. (I know i could use a SSG but i do not know how it will behave with contact forms in elementor so ill leave it for know)

Did I miss a critical setting? Are there hidden options or best practices I should have enabled from day one?

TL;DR: Super Page Cache worked great for 2 days, then client's site broke. Manual cache purge fixed it. No updates were made. What am I fundamentally missing about how this caching setup should work long-term?