https://www.cbr.com/spock-not-in-star-trek-generations/

MOVIE URBAN LEGEND: Leonard Nimoy turned down a chance to appear in and direct Star Trek: Generations due to how little Spock’s dialogue sounded like Spock to him.

Star Trek: Generations was the “bridge” film, as it appeared between the final film to star the original Star Trek crew (Star Trek VI: The Undiscovered Country) and the first film to start the Star Trek: The Next Generation crew (Star Trek: First Contact).

Generations is OK but not as good as the original star trek movies..... I dont blame Spock for not wanting to be in it.........