AFAIK Wahoo added FTMS but didn’t remove Bluetooth Smart Wahoo Trainer Control. A list of modes for Kickr V5 are in the DCRainmaker review Wahoo KICKR V5 (2020) Smart Trainer In-Depth Review | DC Rainmaker
Over here:
TR support stated the app prioritizes FTMS over Wahoo proprietary. The workaround is to downgrade firmware or use another app (e.g. Wahoo) to put the trainer in standard/level mode.