I also run a lot of games off an SD card in my deck. Dragon age veilguard is probably the most demanding I've played off an SD card it didn't have issues.

I know whenever I purchase an SD card for the deck or something demanding I do a decent bit of research. There are a bunch of different terms/specs on SD cards that impact performance, more than just 150 MB/s. Perhaps the SD card you have isn't the best for gaming, or maybe it's a dud card or a crappy manufacturer.