"Deep dissatisfaction" refers to a strong feeling of unhappiness, dissatisfaction, or discontentment that goes beyond just being mildly discontent. It signifies a profound level of dissatisfaction or displeasure with something. Full definition
Over the past month, legislators investigating Russian propaganda on social media have expressed deep dissatisfaction with Twitter for belated and apparently incomplete discoveries — or disclosures — over Russia hijacking the microblogging service. (thedailybeast.com)
The huge march in London at the weekend was in part a roar of deep dissatisfaction at hardline policies in the UK (cuts to legal aid, threats to scrap the Human Rights Act, etc), not just a protest at Trump's divisive rhetoric and policies. (politics.co.uk)
Though he said he does not want to speak negatively about Stefanik's record, he harangued Republicans in general and expressed deep dissatisfaction with the party both locally and nationally. (timesunion.com)