R404A is a near-azeotropic blend of three HFCs. It boils at about −46 °C, gives strong capacity at freezer temperatures and is non-flammable, so for years it was the default for deep freezers, ice-cream cabinets, cold rooms and frozen display cases.
Its GWP is close to 3,900, among the highest of common refrigerants. A cold-room or display-case system holding several kilograms of R404A has a large climate footprint if it leaks. Under the global HFC phase-down, R404A is one of the first gases manufacturers move away from, towards R290 in plug-in equipment, CO2 in larger systems, and lower-GWP HFO blends where non-flammability is needed.
If you run existing R404A equipment, it can still be serviced, but expect gas costs to rise over time. Leak tightness matters more than ever, because every top-up costs money and adds to emissions. Retrofitting to a lower-GWP blend is sometimes possible on larger systems with professional advice; for small plug-in freezers, replacement at end of life is usually more sensible.