Yes, the Canon EOS R5 Mark II is compatible with the Lexar CFexpress Type B Professional Gold 128GB.
Lexar CFexpress Type B Professional Gold 128GB is VPG400 class. Meets the floor for: 4K30 (30 MB/s floor); 4K60 (60 MB/s floor); 4K120 (90 MB/s floor). (Peak write 1500 MB/s is not evidence of sustained performance; the VPG400 class rating above decides this.)
“RAW Standard RAW 29.97 CFexpress 2.0 Type-B [400MB/sec. or faster]”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)