Last updated: June 2026
Roughly 45% of AI-generated code ships with patterns its author never reviewed, and infrastructure budgets for AI-built projects are commonly underestimated by 40–60%. None of this shows up on screen. The app looks finished, so you launch — and the cost arrives later, on the invoice.
1. The expensive stack choice
The biggest cost trap usually isn't code at all — it's where your backend runs. Managed layers like Lovable Cloud are convenient but carry a premium that can reach ~10× a plain backend at scale. We compare the two here.
Fix: own your backend (e.g. your own Supabase project) once growth is real.
2. Queries that read the whole table
AI tools love select('*') with no limit. On a page that lists items, that means every visit downloads all rows and all columns — so your database egress scales with how much data you have, not how much the user sees. Fine at 10 rows; brutal at 10,000.
Fix: add a limit and pagination, and select only the columns you render.
3. Timers that never sleep
A setInterval that refetches every few minutes keeps hitting your database 24/7 — once per open browser tab, whether or not anyone is doing anything. A thousand users with the tab open can generate hundreds of thousands of reads a day for no benefit, forcing a bigger compute tier (or, on Firestore, real per-read charges).
Fix: use realtime subscriptions, or widen the interval and cache.
4. Images served without a CDN
Serving user images straight from object storage means you pay bandwidth on every view — Supabase egress overage runs $0.09/GB past the free tier, and image transformations add up on top.
Fix: front your storage with a CDN and cache transformed images.
5. The free-tier cliff
Every free plan has a ceiling, and crossing it changes the rules:
- Supabase Free: 500 MB database, 5 GB egress, pauses after a week of inactivity. Pro is $25/mo (with a spend cap on by default — a good thing).
- Firebase Blaze: pay-as-you-go with no spend cap. It charges per operation, so a traffic spike or a loose query has no ceiling — the classic surprise-bill story.
- Vercel Hobby: 100 GB bandwidth, and its terms don't allow commercial use — easy to outgrow without noticing.
Fix: know where your ceiling is before you hit it, and set a budget alert.
Find your cost traps in two minutes
A free check reads your stack and flags which of these are hitting you — and roughly at what user count.
Run the free cost check →Want the exact lines, not just the categories? The Cost Report scans your real code and hands you each trap by file and line with a copy-paste fix.