According to ... ... :
Like someone mentioned ,check your local code. Around hereplywood is
allowed but some places require fire rated plywood or a coat of fire
retardant paint.

Indeed. Electrical/Building Code at least in Ontario Canada
_requires_ a fire resistant backing, and everybody uses drywall.
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Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.