Hey there, hope you are doing great.
I just read your description that you need a designer for your different channels related education as I checked some of the links. I just checked some bids on this project but did not find any relevant designer by checking their profiles, who is particularly have passion for thumbnails. Currently I am active on Upwork and Fiverr, so there is not a single review related thumbnails on my profile, but I must say, you can check some thumbnails sample on my portfolio to know about my skills. Actually, I want to build my profile as well on this platform. I will send you my other freelancing platform's profile if you wanna check. Also, can send you some sample designs for your satisfaction without any extra cost. Please try to contact me atleast once. I will not force you if you will not satisfy with my skills. Thanks for reading it. Have a great time.