I too ran into this after an update, poked at it and while I have no solution or idea to the actual cause during update - the exfat driver in use makes a difference.
The latest incarnation of the Samsung exfat driver that made it into mainline and back to 4.9 (and most Linux distributions and Android devices) is more tolerant to what older drivers see as corrupted. Your star2lte still has the older driver but a backport is possible.
If this would avert being initially identified as corrupted I don’t know, but it would make recovery easier.
no tools or commands is present to check, recheck, mount unmount, repair the storages…
true - not through the user interface. Though since Android 9 or 10, “vold” (the internal volume manager) does a fsck.exfat on boot of the sdcard filesystem and will output its result to logcat. With adb root you can do this manually, but it won’t make a difference as it already ran. Just fyi
CC to the now closed SD Card corrupted in phone and all files accessible on computer