Yes, unfortunately.
You will file as a non-resident and be taxed only on the gain.
How California taxes residents, nonresidents, and part-year residents
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California residents - Taxed on ALL income, including income from sources outside California.
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Nonresidents of California - Taxed only on income from California sources.
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Part-year residents of California - Taxed on all income received while a resident and only on income from California sources while a nonresident.
https://www.ftb.ca.gov/individuals/filertn/nonresidents-part-year-residents.shtml#how_taxed
