I often get a similar phenomenon, for better or worse. I kind of have this rule: read the book first if there's a movie/show about it, then watch the movie/show, then read the book again. This helps me avoid "the book is better" (sometimes -- it's a rare case where the audiovisual format excels, but it happens).
First reading I get my imagination and expectations. Watching the movie/show lets me know how others interpreted it.
If it was a well made, casted, and acted depiction, then the 2nd reading often will conjure images of specific scenes, actors, soundtracks, etc. even if it wasn't quite what I imagined initially. If it was a poor adaptation, rereading the book reminds me that my imagination was better.
To date I can only think of two movies that captured their respective novels nearly identically to my imagination (within reason, given content and technological limitations):
- Phillip K Dick / Richard Linklater - A Scanner Darkly
- Michael Crichton / Barry Levinson - Sphere
- Ted Chiang / Denis Villanueve - Story of Your Life (Arrival)
- Bret Easton Ellis / Roger Avery - The Rules of Attraction
- Alex Garland / Danny Boyle - The Beach
I often wonder if the influence of the authors of these books upon the production of the movies was a factor, but I've seen plenty movies where the original author had lots of input/approval and the result was a mess. Dunno.