When you install a new version of the OS - especially a beta version - it has to do some extra work to index files and whatnot. That's why your phone might feel a little warmer than normal for a day or two.
For a beta version there are extra processes enabled that allow Apple to record more info whilst the software is in beta. Those processes are not enabled in release versions.
You just have to give it a little time to settle down.
You also have to understand that you have installed beta software, and there are going to be issues. If you find something you think is a bug in the beta software, raise a feedback report here: https://feedbackassistant.apple.com/
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Community
SubTopic:
Apple Developers
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