There is an updated pull request by TinfoilSubmarine against master on the void-packages repository

https://github.com/TinfoilSubmarine/void-packages synapse
https://github.com/void-linux/void-packages/pull/35109

synapse: update to 1.50.1.
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Supersedes https://github.com/void-linux/void-packages/pull/34676. I packaged `python3-txredisapi` so that users wanting to setup Redis/workers can easily do so, even though it is not a dependency for the base installation of synapse. 

A patch file from https://github.com/void-linux/void-packages/pull/35109.patch is attached