Mac Mini specialist ExpandMacMini.com disassembled the new Mac Mini and found that both models have NAND flash memory soldered directly to the logic board. This means that it is no longer possible to upgrade storage capacity by removing the SSD module as in the past.
Previously, with the M1, M2, and M3 Mac Minis, the SSD was soldered to the logic board, but the M4 and M4 Pro models used detachable SSD modules. This allowed users to increase storage capacity by using aftermarket SSD modules.
However, with the M6 and M5 Pro models, the soldering method has returned, making SSD replacement and upgrades virtually impossible. ExpandMacMini.com also stated that "it seems unlikely that we will be able to support the M6 and M5 Pro at this time" and urged users not to purchase SSD modules for these models.
▶ Original source: https://m.kbench.com/?q=node/282128