Proxy IP masking: What gives?

Hey everyone,

I'm banging my head against the wall with something that *should* be straightforward. I'm working on a pretty critical data collection project for my SaaS, which, as you can imagine, relies super heavily on proxies for IP rotation and anonymity. I thought I had the whole IP masking game pretty much nailed down, investing in what were advertised as "premium" residential proxies. You know, the good stuff, not the dodgy datacenter ones.

But nope. It feels like my IPs are wearing a neon sign that screams "I'M A PROXY, BLOCK ME!" instead of actually doing any effective masking. I'm consistently getting flagged or outright blocked by target sites, even with a fresh rotation. It's truly baffling and honestly a bit amusing how bad the masking performance is turning out to be. Here's a snippet of what I'm constantly seeing:

[2024-07-25 10:34:12] ERROR: Access Denied - Bot Detected (Code: 403)
[2024-07-25 10:34:12] INFO: Request IP detected as: 192.168.1.100 (Expected: US, Actual: Unknown/Proxy Network)
[2024-07-25 10:34:13] WARN: Proxy flagged for suspicious activity. Retrying with new IP...

What gives? What are the common reasons for such consistently poor IP masking performance, especially when using supposedly high-quality residential proxies? Are there any advanced techniques, header configurations, or even specific types of proxies/providers I might be missing to truly bypass these increasingly sophisticated detection systems?