I have Siril installed on an external SSD
(SAMSUNG 990 EVO Plus SSD 4TB (MZ-V9S4T0B/AM) connected to a Hagibis mc25 Pro enclosure. While running DSA-Seestart_Mosaic_Processing script on a 1575 fit file mosaic of M31, the SSD ejects at random times during the processing (usually within the first 10 sec).
I don’t see how it could be Siril’s fault.
Rather, I think the high level of I/O activity is causing the problem and making the connection unstable. But it’s a hardware problem in my opinion.