It's true for HDDs. They don't maintain a list of compatible third-party HDDs, but you use them perfectly fine. No errors, drive health monitoring works, etc.
>Now, with the release of DSM 7.3, Synology has quietly walked the policy back. Third-party hard drives and 2.5-inch SATA SSDs can once again be used without triggering warning messages or reduced functionality. Drives from Seagate, WD, and others will work exactly as they did before—complete with full monitoring, alerts, and storage features.
They still require you to buy their overpriced (even by AI bubble standards) NVMe drives with zero third-party support. There is a project that adds third-party SSD support for newer Synology devices, but you need to redo it every time your NAS updates, so it's very much unsupported. Would definitely not say that they "recanted immediately".
I'm not at all surprised that Ubiquiti is getting ahead of that and promising it from the start.