Yes, the Lexar Professional 2000x 128GB SD UHS-II is compatible with the Sony A7C II.
Sony A7C II Slot 1 accepts full-size SD cards directly, with a Video Speed Class V60 floor for its top-tier S&Q Motion 4K mode (250Mbps). Lexar Professional 2000x 128GB SD UHS-II is V90 class. Meets the floor for: 4K30 (30 MB/s floor); 4K60 (60 MB/s floor). (Peak write 260 MB/s is not evidence of sustained performance; the V90 class rating above decides this.)
“For S&Q Motion shooting (When [ Proxy Recording] is set to [Off] ) File formats and compatible memory cards are as follows. File Format Maximum recordable bit rate when recording Supported memory card XAVC HS 4K 250Mbps SDXC V60 or higher”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)