Yes, the Canon EOS R5 Mark II is compatible with the Sony SF-M Tough Series 128GB SD UHS-II.
Canon EOS R5 Mark II's SD slot (Slot 2) accepts Sony SF-M Tough Series 128GB SD UHS-II directly. Sony SF-M Tough Series 128GB SD UHS-II is V60-rated, clearing the SD slot's 4K Long-GOP floor (up to 119.88fps) but not the 8K Long-GOP floor (needs V90) — no setting or firmware update changes a card's rated speed class. Also, its own card-performance-requirements table shows every RAW, SRAW, and Intra-codec recording mode (XF-HEVC S / XF-AVC S High Quality Intra, Standard Intra, Light Intra) has no SD-card entry at all — those modes are CFexpress-only by design, not just speed-limited. Only Long-GOP (LGOP) compressed modes are SD-eligible.
Limitation
Cannot record 8K Long-GOP (needs V90) or any RAW/SRAW/Intra-codec mode (CFexpress Type B, VPG400 only) on the SD slot. Works for 4K Long-GOP up to 119.88fps and all lower-tier modes.
“Standard LGOP 119.88 CFexpress 2.0 V60 100.00”
Last verified:
Compatibility inferred from spec rule (citations above are manufacturer-verified)