Hi, Ramjan.
It appears the average value of projects per client has dropped over the past year. If your projects are usually in the upper range of average project values, you may be seeing lower responses because there are just fewer active clients now setting up higher value projects on Upwork.
I have also seen a slowdown in my rate of invitations to submit proposals and new project wins so far this year.
Only Upwork knows whether there is typically a significant effect of being Top Rated versus being Top Rated Plus in regards to winning new projects. I don't give it much thought.
