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No. The plugin is not using log4j2 for logging nor it bundles the log4j library at all.
Why are formulas written in LaTeX/AsciiMath/JLatexMath do not work anymore in Confluence 8.x?
This is caused by the changed default output format from PNG → SVG. The AsciiMath syntax cannot be rendered as SVG.
You can change back the default settings in the plugin configuration by unchecking the option 'Default File Format SVG'
Alternative you can explicitly define the output format in each plantuml macro using the 'Output Format' property:
Error rendering macro 'plantuml': null
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