From my experience looking at some free chapters on multiple sites, the don't serve any high resolution images for chapters either. Though I haven't checked any SFW manhwas sites for this so. And most piracy sites just compress them with jpeg or webp, they don't usually touch the resolution of the images.

It's because you didn't used good sources. I'm using tons of good sources and I don't have any issue.

Any recommendations on sources? I'd love to jump in but don't seem to be having much luck on sources in particular. Assuming most of them are of the private variety.

One of the biggest rule of tachiyomi is to not share sources. Sharing it especially on a crowded forum like this can increase the traffic and make the source block tachiyomi.

Here how I get a good source: - I follow the watermark of the thing I'm reading, often the scanlation team have their own website and it has an extension available for it. - The scanlation team put the first chapters on mangadex (maybe as an ad ?), once I get their name, same thing, I'll try to directly get from them.