if you use ublock origin, you can permanently remove pinterest results in google images with the following filter:
www.google.com##.isv-r:has-text(/pinterest.com/)
shameless plug: i've been maintaining a browser extension for a couple of years called 'google images restored' [0] which reverts google images to how it was before 2019. that extension, mixed with the ublock origin filter removing unwanted domains (pinterest, alamy, 123rf, etc), makes google images enjoyable again for me.