Our company was on the committee and drew the symbol for IEC/ISO. The new IEC 61482-1-1 FDIS for arc ratings of garments it the first I know to cite the symbol. The new IEC Guide for Arc Flash Risk assessments will likely recommend the symbol also. Just make sure you use it in accordance with the ISO copyright. Normally it can only be used in conjunction with an ISO standard. This may not apply to end user uses like labels but I would check.
https://www.iso.org/obp/ui#iso:grs:7010:W001ISO says the symbol "cannot be used on its own and requires a supplementary sign to give further information about the hazard."
The use of the Triangle Warning is likely OK but we have been told the symbol with the shield (used for PPE) must have an associated ISO standard on the label which uses the symbol. There is currently no ISO standard or IEC standard for Arc Flash Hazard Assessment.
Good luck.