Is there a term for a person who moves from one field of expertise to a new field and has an inflated belief in their competence in the new field? Person A has led a successful career and is very well renowned in field A.
Later in life, person A moves to field B, a field they're curious about but have very little experience in.

Person A struggles to accept their limited understanding of their new domain, having been an expert in their own domain for so long, and imposes their (usually) incorrect views on a field B topic on others based on a confidence they've built from being good in field A.

Is there a term in psychology for this phenomenon?
Déformation professionnelle is probably the closest match:


  Déformation professionnelle is a French phrase, meaning a tendency to look at things from the point of view of one's own profession rather than from a broader perspective. It is often translated as "professional deformation" or "job conditioning". The implication is that professional training, and its related socialization, often result in a distortion of the way one views the world.[1]


Followed by the law of the instrument / Maslow's hammer:


  The concept known as the law of the instrument, Maslow's hammer, Gavel or a golden hammer[a] is an over-reliance on a familiar tool; as Abraham Maslow said in 1966, "I suppose it is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail."[1]




References
1 [déformation professionelle]. Bönisch, J. (2007, November 30). Déformation professionnelle: Beruflich bedingte Missbildung. Süddeutsche Zeitung. Retrieved from http://www.sueddeutsche.de/karriere/deformation-professionnelle-beruflich-bedingte-missbildung-1.786888.
1 [law of the instrument]. Maslow, A. H. (1966/2004). The psychology of science (pp. 15). Maurice Bassett.