Yes, the Fujifilm X-S20 is compatible with the Samsung PRO Plus 256GB SD.
Samsung PRO Plus 256GB SD is V30 class. Meets the floor for: 4K30 (30 MB/s floor). Does not meet the floor for: 4K60 (60 MB/s floor). (Peak write 90 MB/s is not evidence of sustained performance; the V30 class rating above decides this.)
Limitation
Cannot record at 360 Mbps -- requires Video Speed Class V60 or higher. Works for all lower-bitrate modes (4K30 at standard bitrates, 1080p). Upgrade to V60 or V90 card for full 360 Mbps capability.
“*For recording movies, use a SD memory card with UHS Speed Class 3 or higher. *For recording movies in 360Mbps, use a SD memory card with Video Speed Class 60 or higher. ”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)