Hello! As someone who also went through this nightmare after nearly 15 years on Harvest, I've built what I really believe is a worthy competitor, Zebu: https://zebu.work - for only €5/month. Please feel free to give it a try, I really stand behind it and have been using it for my freelance/studio now and migrated everything from Harvest.

My only real difficulty has been marketing/gaining traction as buying advertising for such a low-fee project has proved very difficult!