Ask HN: What is the hottest OSS software I should contribute to

I mostly program in Go, Java and C++ (been a while since i used C++). I have a lot of spare time with the lockdown situation and would like to use the time to contribute more to open source. I already contributed some small fixes/features to projects like terraform or gogen-avro but would like to do more. I would like a friendly project where I can learn fast or where the community is able to get you to speed.

Any suggestions?