@akwankl same issue was discussed here.
The Product and Engineering teams are currently working on a more permanent solution but I don't believe we have an actual timeframe for this yet.
In the meantime, we have what we call the 'Shared device interim approach', which will require a Support ticket but as you can see below there is the ability to ignore some merged profiles to avoid the risk you mentioned.
At this time we cannot prevent 2+ CRM IDs from merging into 1 graph due to shared device (ECID) or non-unique cross-device identifiers (hashed email / phone), but as an interim approach we can skip merged profiles that use these graphs from segmentation & activation, and lookup
Hope that helps.