Any open source alternative to Microsoft Teams?

I have to deal daily with Microsoft Teams, and it's the slowest software on my PC. I'm running it on Linux (unofficial client, [0]) because the original client is far worse.

Am I the only one that feels the necessity of replacing this software with an open source alternative that is not ss bloated as the software provided by Microsoft? Is somebody working on the side to create an alternative client? I would love to contribute.

[0]: https://github.com/IsmaelMartinez/teams-for-linux