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?

i was using wp super cache by automattic and wordfence, thought it wouldnt hurt to put some clients with $5 web hosting behind cloudflares free tier.

Not because they are under too much attacks or need clients from the us, they only have clients in germany and the servers were in germany.
But when they start their ads or have multiple visitors at the same time these trash servers will crash and serve slow. I changed the nameserver and installed cloudflare plugin, created api token only for that domain, clicked on recommended settings, disabled email address obfuscation and selected

Use the Cloudflare HTTP header "CF-Connecting-IP" to get a visitor's IP address. Only use it if you're using Cloudflare.

under wp-admin/admin.php?page=WordfenceOptions, it warns me with a red box and tells me wrong settings etc. but i think it didnt understand my cloudflare is active so ive dismissed the error warning because cloudflare is definitely active and protecting.

Ive set Cloudflare via Plugin to "Auto Purge Content On Update", the question is now should i change my WordPress Caching Plugin itself or is WP Super Cache already the best free ones.
I do not want to convince clients to pay for any Plugins.

WP Fastest Cache could work too but it is always causing Layout Problems after 2-3 days or with Elementor Sites CSS/JS Problems, i have to set the CSS on inline instead of external.

With WP Super Cache i do not have to do that it can stay in the Elementor Settings "CSS External" plus i deactivate the Elementor Cache and can set compress in the advanced WP Super Cache Settings too. And it does not have any problems after 3-4 days and requires no clearing the cache manually. The problem was using elementor back then in the first place but i cannot check the sites constantly with WP Fastest Cache now,

WP Super Cache works better but ive wanted to ask if theres a better solution for free that works better with Cloudflare or is Automattic already doing us a favor for free.

Ive seen there is a Plugin called wp-cloudflare-page-cache by Optimole

is this better and legit as Automattic or a future security risk?