It is likely the required modification is not sinister at all, and nothing to worry about!
For example, when I was asked to modify my gigs, it was only because the category in which my gigs are listed (writing and translation) had had a few category changes made by Fiverr.
Fiverr had split the category of copy editing into a few new subcategories… aagh! I had been avoiding making any changes prior to that because I knew customer support was low-staffed right now, and I knew that my gigs would need manual review and approval after any changes… So, I wanted to leave my gigs untouched.
However, as Fiverr itself changed the categories, every seller in the editing category then had to make revisions. So, the messages I received forced me to update my gigs and then they disappeared from search until I finally contacted Customer Support, asking for a manual review of the two revised gigs (and re-indexing). Every time we make changes, the gigs go unsearchable until customer support reviews them and puts them back.
So, in my case, I was asked to modify my gigs only because they asked all sellers to check and choose which of the new categories to place the gigs into. (There were a couple of new questions once I opened up each gig. I had to make new category selections). The message asking me to revise my gigs also said that until I had done this, my gigs would lose ranking, so I couldn’t win either way…!
It was just something every seller needed to do for Fiverr to know where to place each gig now that Fiverr had subdivided the categories.
Therefore, it may be that your own ‘mofification needed’ message was for the same reason and that there was nothing ‘wrong’ with your gigs’ content at all
So, Najaf, take a look at every single section of your gigs (in the ‘edit gig’ mode) and ensure each section is fully answered, then save it and it should be ready for Customer Support’s approval once again.
Take your time and do it slowly and calmly because you don’t want to make changes to a gig more than once…do the changes once and then ask Fiverr to please “re-index” them… so that they become searchable again.
Regarding the Customer Success Program, yes, I have a customer success manager and you have to be invited to join the program by Fiverr, personally. It is not something you can apply for or ask to be considered for. If you are selected for the program, a success manager will write to you and arrange to have a 1-1 video chat with you to discuss your gigs, sales, etc, and he/she will help you increase your success here.
I totally understand how worried you are because I was exactly the same when my gigs disappeared offline! It should not be a difficult problem to fix, just make the modifications requested and then ask customer support to get them re-indexed for you.