Hi, I bought a Samsung Galaxy Tab A7 WiFi last week, together with a 256GB SanDisk Ultra microSDXC card. I've made the experience that the SD card gets unusable slow (100 KB/s write speed) when the SD card encryption is enabled. Sometimes the first ~150 MB transfer at normal speed, but eventually it always slows down. Without encryption the sequential write speed is a bit above 20MB/s, which is what I would expect. Unfortunately, encryption is a must have for me and not optional.
Searching the internet, I've found this post that refers to the same problem, but does not come with a solution. I think this is some kind of software bug in the encryption routine. I've installed all updates (security patch level is 1. August 2021).
I hope this problem can be acknowledged and fixed in a future update. Maybe someone has an idea for a workaround.
Edit: Seems like this is a problem other Samsung devices like the A22 5G have too. But, unfortunatly no solution either.