Sitemap generation acting weird?

Hey everyone, hope you're all having a productive week! We run a 'Free XML Sitemap Generator' web tool over here, and for the most part, it's been a real workhorse, churning out sitemaps like a champ. Lately, though, it's started acting a bit... quirky, almost like it's developed a mind of its own and decided some URLs just aren't worth its time. It's been giving us some real head-scratchers with inconsistent results during sitemap generation, especially when it comes to websites with really complex structures or a lot of dynamic content. We're talking about it sometimes completely missing pages, or even worse, stubbornly including weird defunct URLs that should have been banished to the internet graveyard, and on larger sites, it just throws up its hands and times out, leaving us with half-baked sitemaps. We've gone through the usual suspects trying to figure this out, meticulously double-checking our web crawling logic, adjusting every timeout setting we could find, pouring over server logs for any hidden errors during the generation process, and even experimenting with different user-agent strings to try and mimic various bots, hoping to sneak past some defenses. We've thrown it against multiple known-good sites, and observed a frustrating spectrum of success and failure, which just makes it even harder to pinpoint the exact culprit. It's truly baffling, like our sitemap generator is playing a game of hide-and-seek with certain pages. Our current suspicions are swirling around a few possibilities: could it be related to client-side rendering on those heavy JavaScript sites, where content isn't fully available until a browser executes a bunch of code? Or perhaps aggressive server-side caching on the target websites is messing with our crawler, serving it stale or incomplete information? We're also pondering if some obscure, convoluted redirect chains are simply not being handled gracefully by our current crawling setup. Honestly, it's almost like our entire sitemap generation process, especially the web crawling part, is having an existential crisis and questioning its purpose in the digital world. So, I'm reaching out to this brilliant community: has anyone else out there experienced similar erratic behavior with their own sitemap generators or web crawlers when dealing with modern, complex websites? Do you have any specific techniques, libraries, or even just general wisdom for robust crawling that you'd heartily recommend? We're desperately looking for some fresh eyes or common pitfalls that we might be completely overlooking in our quest to tame this beast. Eagerly awaiting some expert wisdom to get our sitemap generator back to its glorious, predictable self!