Access to classified intelligence means that they are allowed to enter a secure room/facility and view the material. They still should not be taking said material out into an unclassified environment.
There are different levels of classification that carry different restrictions. Also, govt infosec being what it is, there are likely plenty of lapses.
Even the lowest level of classification (confidential) means that the data should not be stored on an unclassified system, and has additional physical storage requirements that Pelosi's main office doesn't meet.
At worst, the laptop had FOUO/CUI (for official use only/controlled unclassified information) data. Not great for that to get leaked; but not that scary from a national security perspective (we're pretty aggressive about classifying stuff).
If anything damaging comes out of this, I would expect it to be of a political nature; where something that Pelosi and friends would prefer to keep secret gets leaked, but doesn't have much influence on national security.
