We have received a response from Adobe support and this is how the reply went. The gist is, yes its capped at 128 characters and cannot increase. If we want more characters to be captured it is recommended to send te data to custom eVar that can handle 255 characters.
"Activity Map link in the Activity Map code, there is a limit set to capture the data, which is capped at 128 characters.
You can see this in the code snippet:
["a.activitymap.link"] = 128 < n.length ? n.substring(0, 128) : n;
Now, even if we want to capture the data completely without truncation, you need to capture it in an eVar. The Activity Map data will be captured as context data and will automatically map on the backend.
Therefore, the only option to capture the Activity Map link is by firing the same data that's being captured in the Activity Map link into an eVar. Since eVars have a length of 255 characters, there will be no truncation.
This is a custom implementation that needs to be done on your end, as we will not be able to assist with the custom implementation. However, the only workaround to capture the Activity Map link completely is to capture that in an eVar whenever the Activity Map link is fired in the server call.
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