Lens haze in older cameras is usually caused by one of three things: contamination on glass surfaces, fungus, or separation of cemented lens elements.

Common contamination includes condensed lubricant vapors from shutters/apertures, oil or grease, dust, smoke, moisture residue, or marks left during servicing. If that’s all it is, it can often be cleaned, though internal elements require disassembly and care because inner coatings may be delicate.

Fungus is another common cause and is often identified by a spiderweb-like pattern. It may be removable if caught early, but severe cases can etch the glass.

A more serious problem is balsam/cement separation in bonded elements. This looks like haze but is actually the adhesive between elements failing over time. That is usually not economical to fix on most old lenses.

So yes, haze is often removable if it’s just surface contamination or mild fungus. If the glass itself is corroded/etched or the elements are separating, cleaning won’t solve it and repair is usually impractical.