In November 2023, something happened to OSDN, which had been hosting the Tsukurimashou Project. Here is a chart of traffic from our Matomo analytics covering the period. There is a gap from 16 November 2023 to 18 January 2024, although a couple of visits did register during that period, suggesting that either the site was up for brief intervals, or people were connecting to cached copies, the Wayback Machine, or similar, and triggering the analytics scripts that way. (The analytics server itself has always been on non-OSDN hardware, so it wouldn't've gone down just because the site did.)
The traffic starting in January 2024 after the gap, is on the new site, tsukurimashou.org, where I'm posting this note; the old site on OSDN, tsukurimashou.osdn.jp, appears to be permanently unreachable.
November 2023 was a terrible time for this to happen; I had a lot of other things on my plate and it has taken me until now, February 2024, to put the pieces together and figure out what happened, digging back several years into history that I was unaware of at the time it was happening.