Still on original hoses? If rubber they might be getting a little perished by now.
Check for correct routing and any evidence of chafing.
Look carefully where hose meets banjo. Pump the brake and hope not to see anything like the picture above.
Don’t reuse copper washers when changing brake hoses. They’re cheap enough.
Stainless steel banjoes are best, plated steel next best and avoid aluminium on a road bike.