Multiple SD Card holders rejoice, hot swapping SD cards with your Steam Deck is completely okay! Earlier today, a post circulated on Reddit regarding hot-swapping SD cards. User Diamondjatt asked Valve’s support if hot-swapping, which is just taking your SD card out and putting another one in without any safely ejecting process, was okay. Valve responded saying that no, you should be fully shutting down your Deck before switching out SD Cards or using the Dolphin file browser in desktop mode to safely eject.
Due to this, people were quite confused for a little bit as changing Micro SD Cards in gaming mode whenever was shown off a lot. This prompted a Twitter user, @astnla, to ask Lawrence Yang (developer working on the Deck) if it was true. He replied mentioning it is completely safe to hot-swap, unless you are playing a game off the SD card and he will talk to the support team to correct that information.
Thankfully, we can continue to swap as much as we want. I would also recommend against swapping cards out if you are downloading or writing anything to the SD card.