I have tried reboots of both the phone and laptop numerous times, sometimes together, sometimes one or the other, with no definitive pattern of success. Safe mode didn't provide any better luck. I may have found that if I disconnect all USB devices (I had an external SSD and sometimes an external hard drive attached) except the iPhone, and rebooted both the iPhone and laptop, I could start downloading pictures and videos to Photos through the Photos user interface. The download would stop at some point (hundreds, sometimes a thousand pictures in), at which point if I disconnected the iPhone, wait a few seconds, and reconnect the iPhone, I could continue the download until it stops again. I'm trying to remember if I had to close and reopen Photos - I don't believe I did. Took several rounds of this to download ~7000 pictures and videos.
I found the same pattern was required to download the same pictures and videos through the ImageCapture user interface. In that case, there were closer to 14,000 files to download, with live photos coming in as two files, and any image that had been edited coming in with an addition .AAE file with the edits. I did the download like this so I could import the files into Lightroom, which just couldn't even evaluate duplicates before hanging when trying to import directly from the iPhone. Again, didn't have this problem before the latest OS upgrades, now iOS 18.2 on my iPhone 15 Pro Max and Sequoia 15.1.1.
I have not tried using a new library, using a new user account, or rebuilding my Photos library. One other data point - my wife has an iPhone 15 Pro with iOS 18.1.1, and when I downloaded ~1300 photos and videos to Lightroom, it did so without a hiccup. I don't download her photos to my Photos, so I don't have that data point. Downloading to her Photos on a Monterey iMac didn't have any issues.