Something similar happened in my previous organisation with less than 5 people on the engineering side where I was asked to do a major refactor of the codebase that touched 70% of the files while also adding new features(with changing requirements) at the same time. Though I was working day and night, it took me thrice the time to do it than we initially expected. I was put on PIP after delivering the work(prod deployed) so I left. Then they got 3 engineers from top 1 percentile of industry to work on the same codebase. All this time I was shouting that I need someone to help me in the team but got no one :) . Question mark was put on my performance rather than the management of the team/resources.