Hi @darshil_shah1 , thank you for your response.
The texts in the suppression triggers (email invalid, unsubscribed, Marketing suspended, Email suspended etc) will be dynamic and I would capture these texts via {{lead.Email Invalid Reason}}, {{lead.Unsubscribed Reason}} etc and I have just added them for demo. Also, I am taking Email invalid and Unsubscribed Reasons only as of now for simplicity.
I created the trigger campaign that looks for all the marketing delivarability status to change to False from True as shown below:

However, I tested a couple of scenarios and feels that there is no need to add Suppression Reason filter as I believe the campaign would be triggered anyways if there would be any change in the delivarability status of a person. Please let me know if I am missing any use case here.
In the flow, If I check for Unsubscribed field is "True" , update the Suppression reason to
"Unsubscribed: {{lead.Unsubscribed Reason}}; {{lead.Suppression Reason}}"; in the Default choice (i.e., if the Unsubscribed field is False), then Supression Reason as "Null", then the functionality is not working as Marketo just blanks the Suppression Reason completely, without stampimg {{lead.Email Invalid Reason}} in it. Please refer snapshot below:
Flow:

Result:

This may be due to the fact that Marketo is getting the last value of Suppression Reason from the Default choice as shown in the snapshot above.
Solution: To tackle this, I made a couple of changes in the logic:
1. Clearing out the Suppression Reason field at first, once the campaign triggers in case of any Data value changes in the Suppression triggers from True to false.
2. Once, it clears the Suppression Reason field, I am now checking all the Suppression triggers one by one and including the last Suppression Reason (if any) through {{lead.Suppresion Reason}} after every primary suppression trigger, keeping the default choice as blank now.

Result:

Please let me know if there is any use case which can break down this logic.