Watermark issue on galleries

Hello,
I am facing a strange issue with the watermark feature.
I enabled watermarking from global gallery settings and it displayed watermarks on all the gallery photos.
But I did not want them anymore so I disabled the watermark feature.
However, when I create new galleries or see existing galleries, the watermarks on all the photos still exist.
I tried to reset all settings and even deleted galleries and created new galleries. But still, the problem exists.
How do I remove all the watermarks?
Your earliest help will be much appreciated.
Thanks!

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