Dear @BUR_STEFF
This is possible 🌝
Because the project thumbnail is a 'link' (wrapped around an image) , by disabling the link you wont be able to reach/click the subpage.
You will see online many people advise against disabling links as 'good web practice' but for your reason i think its fine.
Adding the following code into > Lay Options > Custom CSS & HTML > CSS Should do the trick! .
.thumbnail-wrap a{
pointer-events: none;
cursor: default;
}
https://laytheme.com/documentation.html#custom-css-styling
When you are ready to have the links functioning again, you can just remove the code.
Let me know how you go & best wishes 🏖
Richard