Substitution in (multivariate) LaurentPolynomialRing is incorrect

[ghseeli]

Steps To Reproduce

I produced the following code using the Cocalc Sage 10.7 kernel.

sage: A = LaurentPolynomialRing(QQ,['t','x1'])
sage: A.inject_variables()
sage: f = x1 + t^(-2)
sage: g = f.subs({t:t**(-1)})
sage: g
t^2 + x1
sage: list(g)
[(1, t^2), (1, x1)]
sage: g.subs({t:0})
0
sage: list(g)
[(1, t^3), (1, t*x1)]

Expected Behavior

g.subs({t:0}) should return x1. Furthermore, list(g) should be unchanged by any call to .subs() method.

Actual Behavior

g.subs({t:0}) returns 0. Furthermore, list(g) changes after calling .subs() method.

Additional Information

No response

Environment

• OS: Ubuntu 24.04 (Cocalc)
• Sage Version: 10.7 (Cocalc)

Checklist

• I have searched the existing issues for a bug report that matches the one I want to file, without success.
• I have read the documentation and troubleshoot guide