We do not know real read or write approximate speed of your microSD cards (those are all right anyway):
But you can test (actually erase) the microSD cards you mentioned here like this: Librem 5 Phone - SD Speed - #4 by Quarnero. Also and before here linked dd command you might like to start here, by adjusting related command as needed:
Afterwards just go back to already installed Librem 5 Disks app and format used microSD card up to your choice. Good preparation might help, with very same microSD card, I guess.
EDIT: sudo apt install pv