A specific technical term describes the loss of words in a mother tongue when speaking another language

frontiersin.org: First Language Attrition: What It Is, What It Isn't, and What It Can Be. frontiersin.org. https://www.frontiersin.org/journals/human-neuroscience/articles/10.3389/fnhum.2021.686388/pdf

Refers to first language attrition as the technical concept regarding native language loss.

cambridge.org: Network science reveals the early signs of L1 lexical attrition: Introducing the Lexical Attrition Foundation (LeAF) framework | Bilingualism: Language and Cognition | Cambridge Core. cambridge.org. https://www.cambridge.org/core/journals/bilingualism-language-and-cognition/article/network-science-reveals-the-early-signs-of-l1-lexical-attrition-introducing-the-lexical-attrition-foundation-leaf-framework/31DC2AC7FE6A6CDE0AAF595F2F2A9654

Examines lexical attrition regarding the loss of first-language words.

journals.sagepub.com: Inhibiting Your Native Language: The Role of Retrieval-Induced Forgetting During Second-Language Acquisition. journals.sagepub.com. https://journals.sagepub.com/doi/10.1111/j.1467-9280.2007.01844.x

Discusses inhibiting the native language during second-language acquisition.

link.springer.com: Retroactive interference from translation equivalents: Implications for first language forgetting | Memory & Cognition | Springer Nature Link. link.springer.com. https://link.springer.com/article/10.3758/BF03194925

Examines first language forgetting and vocabulary vulnerability after second language exposure.