What did you do with all of the acc?
Did you only posted the same link constantly to different pages/groups?
if yes there is your reason, no normal profile post the same link every day and nothing else.
Anyway can you give more information about your activities with the accounts.
Have you thought about buying sim cards for verification your accounts? This way you can restore all your banned accounts. Also how many groups are you joining per account per day?
Accounts were verified from the seller. Joining 10 groups/day maximum, but every day this action was performed.
The accounts need picture verification. Don't know after this if asks for phone again. 2-3 of them asks just for the phone
Next time make your own acc on the proxies you are planing to use them, it will substantially lover the risk of picture verification.
Also diversify the acc profiles, post some random shit like quotes or anything else like pics on the profiles to make them look more natural.
Edit:
I don't know if massplaner have that option (FL have it), but try to make the url you are sharing (making the pic clickable ) unique every time you post it so it won't look like you are posting the same url constantly.